This is an alternative way to call a function.
The definition of the function doesn't change.
def sumsub(a, b, c=0, d=0):
return a - b + c - d
>>> from funktion1 import sumsub
>>> sumsub(12,4)
8
>>> sumsub(12,4,27,23)
12
>>> sumsub(12,4,d=27)
Keyword parameters can only be those, which haven't been used as postional parameters.