A suitable 'do nothing' lambda expression in python?

Question

I sometimes find myself wanting to make placeholder \'do nothing\' lambda expressions, similar to saying:

def do_nothing(*args):
    pass

B

Answer 1

In Python 3 you don't even need to define any functions for that. Calling type(None) will return you the NoneType constructor, which you can use for doing nothing: type(None)(). Keep in mind that the NoneType constructor only takes 0 arguments.

In Python 2, though, creating instances of NoneType is impossible, so lambda: None would make the most sense.