reload file in Python interactive session?

I want to load this source code ( in Python3 interactive session:

def fib(x):
    if x<7:
        return x
    return fib(x-1)+fib(x-2)


from fib_src import *

to make it easier call the function with only


The problem comes when I modify the source code because I need reload the file with:

from importlib import reload

But if you notice, I never import the whole module. Accordingly, it sends me an error: NameError: name 'fib_src' is not defined

How can I solve it? (I know that importing with "import fib_src" is solved, but that makes me call to the function with fib_src.fib(num) wich is impractical )