Execute function only if a variable is True

Question

I would like to run a function only if a statement is True. For example, i have:

def foo():
    # do something

And i want to run this only when

var == True

And in key handler I don't want to do something like this:

if k.key() == Key_UP and var:
    foo()

I call this function from multiple places and I don't want to repeat var condition. Also, I don't want something like this:

def foo():
    if var:
        # do something

The last one I showed is the nearest to my needs, but still i think it can be done some other way. Idiomatic for Python 3.

Greetings!

PS. I want to get something like this:

def foo() if var == True:
    # do something

Answer 1

Like this?

 def foo():
    print('foo')

>>> bool = True
>>> if bool: foo()
foo

>>> bool = False
>>> if bool: foo()

If the above isn't suitable, I don't think it's clear what you'd like to do or why something like this wouldn't work:

def foo():
    if not var:
        return