User-defined function to reset variables?

[Gribouillis]

I'm thinking about creating a user-defined function where the variables common to all three places are reset to 0.

This is why classes were invented: to group in a single entity variables shared by different places. So create a class (or several classes) to hold the variables

class Foo:
    def __init__(self):
        self.reset()

    def reset(self):
        self.baz = 10
        self.bar = 'hello'
        self.spam = 3.14159

foo = Foo()
...
...
if ...:
    ...
    foo.reset()