<s>[INST] What is the 'cls' variable used in python classes? Why is 'cls' used instead of 'self'?
Any help appreciated
 [/INST] The distinction between "self" and "cls" is defined in PEP 8 . As Adrien said, this is not a mandatory. It's a coding style. PEP 8 says:

Function and method arguments:
Always use self for the first argument to instance methods.
Always use cls for the first argument to class methods.

 </s>