Real Python: Python's None: Null in Python

If you have experience with other programming languages, like C or Java, then you’ve probably heard of the concept of null. Many languages use this to represent a pointer that doesn’t point to anything, to denote when a variable is empty, or to mark default parameters that you haven’t yet supplied. null is often defined to be 0 in those languages, but null in Python is different.

Python uses the keywordNone to define null objects and variables. While None does serve some of the same purposes as null in other languages, it’s another beast entirely. As the null in Python, None is not defined to be 0 or any other value. In Python, None is an object and a first-class citizen!

In this course, you’ll learn:

• What None is and how to test for it
• When and why to use None as a default parameter
• What None and NoneType mean in your traceback
• How to use None in type checking
• How null in Python works under the hood

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