Where to put the global keyword when assigning variables outside a function?

[new_to_python]

Hello, I came across the following code:

a = None

def bind_a_variable():
  global a
  a = []

bind_a_variable()

It is stated that assigning variables outside of the function's scope is possible but those variables must be declared as global via the global keyboard. I am a C programmer. In C, we have to declare a variable first before using it. I would declare global a before

a = None

. However, in the example, a is declared inside a function and after the

a = None 

assignment. Could anybody please clarify?