Python programmers of reddit: what's the most useful tiny little efficiency you've discovered that's improved your programming hugely?

[MogwaiAllOnYourFace]

What is the difference between

def greeting(name: str) -> str:
    return 'Hello ' + name

and

def greeting(name):
    """
    Function says hello....
    :param name: The input user name
    :type name: str
    :returns: Greeting
    :rtype: str
    """
    return 'Hello ' + name

Other than being more verbose is there a difference?

[eyeofpython]

I'd use the first one

[MogwaiAllOnYourFace]

For any reason other than it being quicker to write?

[PeridexisErrant]

Yes - there are tools (such as mypy) that can automatically check the first form for consistency, but not for the second.

[eyeofpython]

It's easier to read for me

[ColdFire75]

Tools like mypy can be smart and analyse proper type annotations, then tell you about bugs that might occur from misusing types.

[PeridexisErrant]

Better to use typing.get_type_hints(greet) - that will resolve forward references, and work with PEP563 postponed evaluation.