Call function outside __main__ function python

If I want to explain the problem in a simplified way, I have two A.ipynb and B.ipynb files. In file B I call a function from outside of __main__ in file A but I can not access it and give NameError: name 'do' is not defined error.
File A.ipynb:

if __name__ == "__main__":
    def do(value):
        print(value)

def func(value):
    do(value)

File B.ipynb:

import import_ipynb
from A import *

func('some text')

I want to see 'some text' as output in console when file B executed. I think Something like (in any way that can be done):

def func(value):
    main().do(value)

can solve problem.