This book is about Python programming, but it is not an introduction to Python programming. It supposes that the reader is already familiar with the Python programming language. Moreover, asynchronous programming is not easy to comprehend at first. For this, some knowledge on computer science can help but is not mandatory. This book contains a lot of code samples and diagrams. In order to test these code samples, a computer with the following software is needed:

• A personal computer with either a Linux distribution, macOS X, or Windows
• Python already installed, at least Python 3.6
• A code editor or an IDE to view and modify the code provided

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packt.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the SUPPORT tab.
3. Click on Code Downloads & Errata.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Hands-On-Reactive-Programming-with-Python. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "In the RxPY implementation, operators are methods of the Observable class."

A block of code is set as follows:

Observable.from_(...)
 .filter()
 .distinct()
 .take(20)
 .map(...)

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

argv.subscribe(
    on_next=lambda i: print("on_next: {}".format(i)),
    on_error=lambda e: print("on_error: {}".format(e)),
    on_completed=lambda: print("on_completed"))

Any command-line input or output is written as follows:

$ source venv-rx/bin/activate
(venv-rx)$ pip install rx

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "By definition, any program has to deal with external events through inputs/outputs (I/O)."