Bringing two files together

[ThiefOfTime]

I suspect that the class A is in a file named a.py and the class B is in a file named b.py, right?
remove the . infront of the a and b. What it does right now is that it looks in the __main__ module where it doesn't find the files a and b. Where did you place the files? Are they in the same directory? If so, just write:

from a import A
 
class B(A)
    def bar(self):
        print('B.bar')