The thing that makes the argument truely optional is the '= <value>' in the parameter list - the Optional [...] annotation is irrelevant as to whether the argument is positional or optional.

Jun 12, 2009 · Python: Python is “pass-by-object-reference”, of which it is often said: “Object references are passed by value.” (read here). Both the caller and the function refer to the …

In Python 3 - Yes, you can specify * in the argument list. From docs: Parameters after “*” or “*identifier” are keyword-only parameters and may only be passed used keyword arguments.

Apr 7, 2017 · Python doesn't know that you are calling the function with the proper types, and expects the programmer to take care of that. If your function will be called with different types …

A single star means that the variable 'a' will be a tuple of extra parameters that were supplied to the function. The double star means the variable 'kw' will be a variable-size dictionary of extra …

56 Writing a decorator that works with and without parameter is a challenge because Python expects completely different behavior in these two cases! Many answers have tried to work …

How to document methods with parameters using Python's documentation strings? PEP 257 gives this example: def complex (real=0.0, imag=0.0): """Form a complex number. Keyword

Jul 16, 2018 · As said in the official glossary under the word parameter: keyword-only: specifies an argument that can be supplied only by keyword. Keyword-only parameters can be defined …

For a language-agnostic consideration of the design decision, see What is the advantage of having this/self pointer mandatory explicit?. To close debugging questions where OP omitted a …

15 In Python 3.+ with the Signature object at hand, an easy way to get a mapping between argument names to values, is using the Signature's bind() method! For example, here is a …