Download or read book Drush for Developers Second Edition written by Juampy Novillo Requena and published by Packt Publishing Ltd. This book was released on 2015-01-29 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a best fit for backend developers with a basic knowledge of Drupal's APIs and some experience using the command line. Perhaps you already worked on one or two Drupal projects, but have never dived deep into Drush's toolset. In any case, this book will give you a lot of advice by covering real-world challenges in Drupal projects that can be solved using Drush.

Download or read book Drupal 8 Development Cookbook written by Matt Glaman and published by . This book was released on 2016-03-08 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over 60 hands-on recipes that get you acquainted with Drupal 8's features and help you harness its powerAbout This Book- Discover the enhanced content authoring experience that comes with Drupal 8 and how to customize it- Take advantage of the broadened multilingual and tools of the new version to provide an internationalized website- This step-by-step guide will show you how to deploy from development, staging, and production of a website with Drupal 8's brand new configuration management systemWho This Book Is ForThis book is for those have been working with Drupal, such as site builders, back-end developers, and front-end developers, and who are eager to see what awaits when they start using Drupal 8What You Will Learn- Extend Drupal through contributed or custom modules and themes- Develop an internationalized website with Drupal's multilingual tools- Integrate third-party front-end and back-end libraries with Drupal- Turn Drupal into a web services provider using REST- Create a mobile-first responsive Drupal application- Run SimpleTest and PHPUnit to test Drupal- Understand the plugin system that powers many of Drupal 8's new APIs to extend its functionality- Get to grips with the mechanics of the configuration management system and the ability to import and export site configurationIn DetailBegan as a message board, Drupal today is open source software maintained and developed by a community of over 1,000,000 users and developers. Drupal is used by numerous local businesses to global corporations and diverse organizations all across the globe. With Drupal 8?s recent release and the exciting features it brings, this book will be your go-to guide to experimenting with all of these features through helpful recipes.We'll start by showing you how to customize and configure the Drupal environment as per your requirements, as well as how to install third-party libraries and then use them in the Drupal environment. Then we will move on to creating blocks and custom modules with the help of libraries. We will show you to use the latest mobile-first feature of Drupal 8, which will help you make your apps responsive across all the major platforms. This book will also show you how to incorporate multilingual facilities in your sites, use web services and third-party plugins with your applications from inside Drupal 8, and test and deploy your appsStyle and approachThis practical, recipe-based book will provide you with actionable techniques and methods to improve your existing Drupal development skills. It will get you started with Drupal 8 and will be your reference guide to building new applications with Drupal.

Download or read book Drupal 8 Module Development written by Daniel Sipos and published by . This book was released on 2017-10-27 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn to create and customize impressive Drupal 8 modules to extend your website's functionalitiesAbout This Book* Unleash the power of Drupal 8 programming by creating efficient modules and extensions* Explore a plethora of Drupal 8 APIs and get the best out of them using the power of PHP coding* Learn to implement efficient data management and data security by creating dedicated modules for it. Who This Book Is ForThe primary target of this book is Drupal developers who want to learn how to write modules and carry out development in Drupal 8. It is also intended for Drupal site builders and PHP developers who have basic Object Oriented Programming skills.A little bit of Symfony experience is helpful but not mandatory.What You Will Learn* Write a Drupal 8 module with custom functionality and hook into various extension points* Master numerous Drupal 8 sub-systems and APIs* Model, store, and manipulate data in various ways and for various purposes* Display data and content in a presentable and secure way* Learn about the theme system and render arraysIn DetailDrupal is an open source web-based content management system (CMS) that can be used for building anything from simple websites to complex applications. It enables individuals and organizations to build platforms that engage users and deliver the right content at the right time.Drupal 8 is an exciting new development in the Drupal community. However, the differences from the previous version are substantial and this can put quite some pressure on Drupal 7 developers that need to catch up. This book aims to help such developers in getting up to speed with Drupal 8 module development.The book first introduces you to the Drupal 8 architecture and its subsystems before diving into creating your first module with basic functionality. Building upon that, you will cover many core APIs and functionalities available to module developers.You will work with the Drupal logging and mailing systems, learn how to output data using the theme layer and work with menus and links programmatically. Then, you will learn how to work with different kinds of data storages, create custom entities, field types and leverage the Database API for lower level database queries. Moreover, you will learn about the Drupal 8 access system and caching layer as well as the APIs used for data processing (queues and batches).You will further see how to introduce javascript into your module, work with the various file systems and ensure the code you write works on multilingual sites. Finally, you will learn how to programmatically work with Views, write automated tests for your functionality and also write secure code in general.By the end of the book, you will have learned how to develop your own custom module from scratch that can help solve a small problem or even provide complex functionality. And who knows, maybe you'll even contribute it back to the Drupal community.Style and approachThis book aims to introduce PHP developers to programming concepts specific to Drupal 8 to get them started on writing their own functionality with Drupal 8 and create efficient Drupal 8 modules and extensions.

Download or read book Drupal 8 Module Development written by Daniel Sipos and published by Packt Publishing Ltd. This book was released on 2019-03-28 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: Learn to create and customize impressive Drupal 8 modules to extend your website's functionalities Key FeaturesExplore a plethora of Drupal 8 APIs and get the best out of them using the power of PHP codingLearn to implement efficient data management and data security by creating dedicated modules for it.Stay up to date with the changes introduced in the new Drupal 8 releasesBook Description Drupal 8 comes with a release cycle that allows for new functionality to be added at a much faster pace. However, this also means code deprecations and changing architecture that you need to stay on top of. This book updates the first edition and includes the new functionality introduced in versions up to, and including 8.7. The book will first introduce you to the Drupal 8 architecture and its subsystems before diving into creating your first module with basic functionality. You will work with the Drupal logging and mailing systems, learn how to output data using the theme layer and work with menus and links programmatically. Then, you will learn how to work with different kinds of data storages, create custom entities, field types and leverage the Database API for lower level database queries. You will further see how to introduce JavaScript into your module, work with the various file systems and ensure the code you write works on multilingual sites. Finally, you will learn how to programmatically work with Views, write automated tests for your functionality and also write secure code in general. By the end, you will have learned how to develop your own custom module that can provide complex business solutions. And who knows, maybe you’ll even contribute it back to the Drupal community. Foreword by Dries Buytaert, founder of Drupal. What you will learnDevelop Drupal 8 modules that do all the things you wantMaster numerous Drupal 8 sub-systems and APIs in the process Model, store, manipulate and process data to serve your purposesDisplay data and content in a clean and secure way using the Drupal 8 theme systemTest your business logic to prevent regressionsStay ahead of the curve and write code following the current best practicesWho this book is for The primary target of this book is Drupal developers who want to learn how to write modules and develop in Drupal 8. It is also intended for Drupal site builders and PHP developers who have basic Object Oriented Programming skills. A little bit of Symfony experience is helpful but not mandatory.

Download or read book Drupal 10 Masterclass written by Adam Bergstein and published by Packt Publishing Ltd. This book was released on 2023-12-15 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: Get started with Drupal 10 using this comprehensive guide for beginners and learn key concepts such as building, installing, maintaining, managing content, and advanced topics through real-world examples and use cases Key Features Explore Drupal 10 concepts in depth and discover how you can engage with the Drupal open-source community Build Drupal applications with powerful features such as structured content, media, views, and displays Learn how to create modules and themes with metadata, hooks, and Drupal’s customization plugins Purchase of the print or Kindle book includes a free PDF eBook Book DescriptionLearning Drupal can be challenging because of its robust, extensible, and powerful capability for digital experiences, making it difficult for beginners to grasp and use it for application development. If you’re looking to break into Drupal with hands-on knowledge, this Drupal 10 Masterclass is for you. With this book, you’ll gain a thorough knowledge of Drupal by understanding its core concepts, including its technical architecture, frontend, backend, framework, and latest features. Equipped with foundational knowledge, you’ll bootstrap and install your first project with expert guidance on maintaining Drupal applications. Progressively, you’ll build applications using Drupal’s core features such as content structures, multilingual support, users, roles, Views, search, and digital assets. You’ll discover techniques for developing modules and themes and harness Drupal’s robust content management through layout builder, blocks, and content workflows. The book familiarizes you with prominent tools such as Git, Drush, and Composer for code deployments and DevOps practices for Drupal application management. You’ll also explore advanced use cases for content migration and multisite implementation, extending your application’s capabilities. By the end of this book, you’ll not only have learned how to build a successful Drupal application but may also find yourself contributing to the Drupal community.What you will learn Understand Drupal’s architecture and infrastructure dependencies Bootstrap, install, and configure your first Drupal project Maintain Drupal through updates, automation, and DevOps practices Harness Drupal features like multilingual, search, Views, and content moderation Understand content management and how to effectively put it into action Explore advanced topics such as Git, Drush, DevOps, and Composer Leverage Drupal’s framework for modules and themes Discover advanced use cases for migration and multisite management Who this book is for If you are a CMS professional new to Drupal and want to learn all aspects of building and maintaining Drupal websites, this book is for you. While hands-on experience with Drupal is not assumed, having foundational knowledge of CMS development will help you get the most out of this book.

Download or read book Mastering Drupal 8 written by Chaz Chumley and published by Packt Publishing Ltd. This book was released on 2017-07-27 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mastering Drupal can lead to a mighty website - discover what Drupal 8 can really do with hidden techniques, best practices, and more! Key Features The most up-to-date advanced practical guide on Drupal 8 with an in-depth look at all the advanced new features such as authoring, HTML markup, built-in web services, and more If you are looking to dive deep into Drupal 8 and create industry-standard web apps, then this is the ideal book for you All the code and examples are explained in great detail to help you in the development process Book Description Drupal is an open source content management system trusted by governments and organizations around the globe to run their websites. It brings with it extensive content authoring tools, reliable performance, and a proven track record of security. The community of more than 1,000,000 developers, designers, editors, and others have developed and maintained a wealth of modules, themes, and other add-ons to help you build a dynamic web experience. Drupal 8 is the latest release of the Drupal built on the Symfony2 framework. This is the largest change to the Drupal project in its history. The entire API of Drupal has been rebuilt using Symfony and everything from the administrative UI to themes to custom module development has been affected. This book will cover everything you need to plan and build a complete website using Drupal 8. It will provide a clear and concise walkthrough of the more than 200 new features and improvements introduced in Drupal core. In this book, you will learn advanced site building techniques, create and modify themes using Twig, create custom modules using the new Drupal API, explore the new REST and Multilingual functionality, import, and export Configuration, and learn how to migrate from earlier versions of Drupal. What you will learn Discover how to better manage content using custom blocks and views Display content in multiple ways, taking advantage of display modes Create custom modules with YAML and Symfony 2 Easily translate content using the new multilingual capabilities Use RESTful services and JavaScript frameworks to build headless websites Manage Drupal configuration from one server to another easily Who this book is for This book is ideally suited to web developers, designers, and web administrators who want to dive deep into Drupal. Previous experience with Drupal is a must to unleash the full potential of this book.

Download or read book Drupal 9 Module Development written by Daniel Sipos and published by Packt Publishing Ltd. This book was released on 2020-08-14 with total page 626 pages. Available in PDF, EPUB and Kindle. Book excerpt: Build and extend flexible Drupal sites and applications with this up-to-date, expert guide to Drupal 9 module development Key FeaturesExplore the essential Drupal 9 APIs for module developmentLearn how to implement data modeling, caching, architecture, and much more in your Drupal applicationsDiscover what’s new in the latest Drupal core releasesBook Description With its latest release, Drupal 9, the popular open source CMS platform has been updated with new functionalities for building complex Drupal apps with ease. This third edition of the Drupal Module Development guide covers these new Drupal features, helping you to stay on top of code deprecations and the changing architecture with every release. The book starts by introducing you to the Drupal 9 architecture and its subsystems before showing you how to create your first module with basic functionality. You’ll explore the Drupal logging and mailing systems, learn how to output data using the theme layer, and work with menus and links programmatically. Once you’ve understood the different kinds of data storage, this Drupal guide will demonstrate how to create custom entities and field types and leverage the Database API for lower-level database queries. You’ll also learn how to introduce JavaScript into your module, work with various file systems, and ensure that your code works on multilingual sites. Finally, you’ll work with Views, create automated tests for your functionality, and write secure code. By the end of the book, you’ll have learned how to develop custom modules that can provide solutions to complex business problems, and who knows, maybe you’ll even contribute to the Drupal community! What you will learnDevelop custom Drupal 9 modules for your applicationsMaster different Drupal 9 subsystems and APIsModel, store, manipulate, and process data for effective data managementDisplay data and content in a clean and secure way using the theme systemTest your business logic to prevent regressionStay ahead of the curve and write PHP code by implementing best practicesWho this book is for If you are a Drupal developer looking to learn Drupal 9 to write modules for your sites, this book is for you. Drupal site builders and PHP developers with basic object-oriented programming skills will also find this book helpful. Although not necessary, some Symfony experience will help with understanding concepts easily.

Download or read book Pro Drupal as an Enterprise Development Platform written by Jamie Kurtz and published by Apress. This book was released on 2014-01-23 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Pro Drupal as an Enterprise Development Platform authors Jamie Kurtz and Thomas Besluau explain how developers can save themselves time and money, and build their applications faster with fewer bugs by using the Drupal CMS as a foundation for their projects. The days when custom client applications were built entirely from scratch are over. Today, it makes business sense to use a flexible, highly scalable framework such as Drupal, Joomla or DotNetNuke as a foundation. This book focuses on why Drupal makes a particularly strong choice for the majority of developers. With an unprecedented level of community support, tens of thousands of well-proven plug-ins and modules available for download, and advanced content management rules and configuration engines Drupal is flexible enough to provide a firm base upon which almost all enterprise application developers can build their own custom solutions. As this book will make clear, it is no longer necessary for developers to write complex applications entirely from scratch for each of their clients. Instead,they should begin by using an enterprise-class CMS like Drupal to provide a robust foundation for them so that they can concentrate their time and skills into solving the business-specific problems of each individual client maximizing the value that they add to each assignment.

Download or read book Serious Python written by Julien Danjou and published by No Starch Press. This book was released on 2018-12-31 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: An indispensable collection of practical tips and real-world advice for tackling common Python problems and taking your code to the next level. Features interviews with high-profile Python developers who share their tips, tricks, best practices, and real-world advice gleaned from years of experience. Sharpen your Python skills as you dive deep into the Python programming language with Serious Python. You'll cover a range of advanced topics like multithreading and memorization, get advice from experts on things like designing APIs and dealing with databases, and learn Python internals to help you gain a deeper understanding of the language itself. Written for developers and experienced programmers, Serious Python brings together over 15 years of Python experience to teach you how to avoid common mistakes, write code more efficiently, and build better programs in less time. As you make your way through the book's extensive tutorials, you'll learn how to start a project and tackle topics like versioning, layouts, coding style, and automated checks. You'll learn how to package your software for distribution, optimize performance, use the right data structures, define functions efficiently, pick the right libraries, build future-proof programs, and optimize your programs down to the bytecode. You'll also learn how to: - Make and use effective decorators and methods, including abstract, static, and class methods - Employ Python for functional programming using generators, pure functions, and functional functions - Extend flake8 to work with the abstract syntax tree (AST) to introduce more sophisticated automatic checks into your programs - Apply dynamic performance analysis to identify bottlenecks in your code - Work with relational databases and effectively manage and stream data with PostgreSQL If you've been looking for a way to take your Python skills from good to great, Serious Python will help you get there. Learn from the experts and get seriously good at Python with Serious Python!

Download or read book Programmer s Guide to Drupal written by Jennifer Hodgdon and published by "O'Reilly Media, Inc.". This book was released on 2015-10-13 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: If you’re a web programmer, your experiences have taught you certain lessons—and only some of them apply well to Drupal. Drupal has its own set of programming principles that require a different approach, and many programmers make mistakes when relying on skills they’ve used for other projects. This book will show you which programming techniques you can use—and which you should avoid—when building web applications with this popular content management framework. Updated to cover both Drupal 7 and Drupal 8, the guidelines in this book demonstrate which programming practices conform to the "Drupal way" and which don’t. The book also serves as an excellent guide for Drupal 7 programmers looking to make the transition to Drupal 8. Get an overview of Drupal, including Drupal core and add-on modules and themes Learn Drupal’s basic programming principles, such as the ability to customize behavior and output with hooks Compare Drupal 7 and Drupal 8 programming methods, APIs, and concepts Discover common Drupal programming mistakes—and why hacking is one of them Explore specific areas where you can put your programming skills to work Learn about the new object-oriented Drupal 8 API, including plugins and services

Download or read book Beginning Drupal written by Jacob Redding and published by John Wiley & Sons. This book was released on 2010-04-20 with total page 613 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough introduction that lessens the learning curve to building sites with Drupal 7 Drupal 7 is the latest version of the free, open source content management system Drupal. A powerful content management system and framework Drupal has an unfortunate reputation of having a steep learning curve. This guide to Drupal 7 methodically demystifies Drupal and shortening the learning curve. Author Jacob Redding is deeply embedded in the Drupal community, and walks first-time Drupal developers through the installation and configuration of a Drupal system. In-depth information on key areas of Drupal explore the Drupal hook system, Drupal's theming layer, and Drupal's API. You'll also get sample code, and lessons that guide you through various aspects of Drupal. Introduces you to every aspect of Drupal 7 Demystifies key areas of Drupal and shortens the learning curve for even the most novice beginner Features lessons and sample code that offer extra insight into a Drupal web site Exploring simple single website installations and more advanced multiple site installations that share users and/or content. Addresses how to use Drupal's theming layer to your advantage. With this comprehensive and clear book by your side, you will quickly learn to leverage Drupal's impressive power.

Download or read book Drupal 8 Enterprise Web Development written by Nick Abbott and published by Packt Publishing Ltd. This book was released on 2016-12-30 with total page 1005 pages. Available in PDF, EPUB and Kindle. Book excerpt: Harness the power of Drupal 8 to create enterprise-grade, highly scalable websites About This Book Build complete, complex websites with no prior knowledge of web development entirely using the intuitive Drupal user interface Ensure your sites are modern, responsive and mobile-friendly through utilizing the full features available in Drupal 8 Quickly master theme administration, custom block layouts, views, and the Twig template structure Who This Book Is For This course is suitable for web developers, designers, as well as web administrators who are keen on building modern, scalable websites using Drupal 8 and its wide range of new features What You Will Learn Set up a local “stack” development environment and install your first Drupal 8 site Find out what is available in the Drupal 8 core Integrate third-party front-end and back-end libraries with Drupal Understand the plugin system that powers many of Drupal 8's new APIs to extend its functionality Build custom block layouts with reusable and fieldable blocks Work with the new Twig PHP templating engine Develop a theme from scratch following a step-by-step project outline In Detail This Drupal 8 course takes you through the journey of building, extending, and customizing websites to build highly scalable and enterprise-ready websites. The first part—Learning Drupal 8—takes you step by step through building a Drupal 8 website. You will start with the basics, such as setting up a local “stack” development environment and installing your first Drupal 8 site, then we move on to image and media handling and extending Drupal modules. This section will help you get to grips with the modular nature of Drupal, and you'll learn how to extend it by adding new functionalities to create your new modules. After learning to develop and manage a modern and responsive website using Drupal 8, you'll start exploring different techniques to take advantage of the new Drupal 8 features. The next module—Drupal 8 Development Cookbook—is your go-to guide to experimenting with all of Drupal 8's features through helpful recipes. You will explore techniques to customize and configure the Drupal environment, create blocks and custom modules, as well as make your web apps responsive by harnessing the mobile-first feature of Drupal 8. This module will also show you how to incorporate multilingual facilities in your sites, use web services and third-party plugins with your applications from inside Drupal 8, and test and deploy your apps. In the third part—Drupal 8 Theming with Twig—you will master Drupal 8's new Twig templating engine to customize the look and feel of your website. This section will walk you through a real-world project to create a Twig theme from concept to completion while adopting best practices to implement CSS frameworks and JavaScript libraries. You will see just how quick and easy it is to create beautiful, responsive Drupal 8 websites while avoiding the common mistakes that many front-end developers make. By the end, you will have learned how to develop, manage, extend, and customize an enterprise-level website. This Learning Path combines some of the best that Packt has to offer in one complete, curated package. It includes content from the following Packt products: Learning Drupal 8 by Nick Abbott and Richard Jones Drupal 8 Development Cookbook by Matt Glaman Drupal 8 Theming with Twig by Chaz Chumley Style and approach This course offers a thorough coverage of developing, managing, extending, and designing highly scalable websites using the Drupal 8 platform. Filled with practical examples and recipes, this course is a great combination of example-driven learning complemented by interesting techniques to take advantage of the Drupal platform.

Download or read book Programmer s Guide to Drupal written by Jennifer Hodgdon and published by "O'Reilly Media, Inc.". This book was released on 2013 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Principles, Practices, and Pitfalls"--Cover.

Download or read book An Investigation of the Effects of the Time Lag Due to Long Transmission Distances Upon Remote Control written by James L. Adams and published by . This book was released on 1961 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book concrete5 Beginner s Guide 2nd Edition written by Remo Laubacher and published by Packt Publishing Ltd. This book was released on 2013-04-23 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a beginner's guide, which takes a clear, step-by-step approach to guide you through the process of creating and adding functionality to your site.This book is ideal for developers experienced with HTML and CSS and possibly PHP as well as JavaScript, who would like to build their first site with Concrete5. Some knowledge of PHP, MySQL, or HTML would be useful, but no experience with Concrete5 is expected.

Download or read book Drupal for Designers written by Dani Nordin and published by "O'Reilly Media, Inc.". This book was released on 2012-07-11 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: Are you a solo web designer or part of a small team itching to build interesting projects with Drupal? This hands-on book provides the tools and techniques to get you going. Award-winning designer Dani Nordin guides you through site planning, teaches you how to create solid, user-centered design for the Drupal framework, and shows you tricks for using real, honest-to-goodness, developer Ninja Magick. This book is a compilation of three short guides—Planning Drupal Projects, Design and Prototyping for Drupal, and Drupal Development Tricks for Designers—plus exclusive "director’s material." If you’re familiar with HTML and CSS, but struggling with Drupal’s learning curve, this is the book you’ve been looking for. Get extra material, including an expanded Grids chapter, more recommended modules, and a Short Form Project plan Learn how to work user-centered design practices into Drupal projects Choose the right modules for your project, and discover several go-to modules Use strategies for sketching, wireframing, and designing effective layouts Manage Drupal’s markup, including code generated by the powerful Views module Learn how to work with Drupal on the command line Set up your development environment and collaborate with other designers and developers Learn the basics of Git, the free open source version control system

Download or read book Python Crash Course written by Eric Matthes and published by No Starch Press. This book was released on 2015-11-01 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: Python Crash Course is a fast-paced, thorough introduction to Python that will have you writing programs, solving problems, and making things that work in no time. In the first half of the book, you’ll learn about basic programming concepts, such as lists, dictionaries, classes, and loops, and practice writing clean and readable code with exercises for each topic. You’ll also learn how to make your programs interactive and how to test your code safely before adding it to a project. In the second half of the book, you’ll put your new knowledge into practice with three substantial projects: a Space Invaders–inspired arcade game, data visualizations with Python’s super-handy libraries, and a simple web app you can deploy online. As you work through Python Crash Course you’ll learn how to: –Use powerful Python libraries and tools, including matplotlib, NumPy, and Pygal –Make 2D games that respond to keypresses and mouse clicks, and that grow more difficult as the game progresses –Work with data to generate interactive visualizations –Create and customize Web apps and deploy them safely online –Deal with mistakes and errors so you can solve your own programming problems If you’ve been thinking seriously about digging into programming, Python Crash Course will get you up to speed and have you writing real programs fast. Why wait any longer? Start your engines and code! Uses Python 2 and 3