Python None

Python defines a special object called the None object or Python None that represents an empty value. The None object is returned by functions and methods that do not have a return value. The None object has no value and prints as None. For example

>>> a = [1, 3, 7, 5] 
>>> print(a.sort())
None
>>> import sys 
>>> x = sys.path.append('.')
>>> print(x)
None