In my code below, why is it the case that isdigit is written with a dot, it's name, and then parentheses to call it, whereas with length this is written with parentheses surrounding zip_code? Are they not both things acting on the object zip_code? def is_valid_zip(zip_code): """Returns whether the input string is a valid (5 digit) zip code """ return zip_code.isdigit() and len(zip_code) == 5 i.e. why is is not... isdigit(zip_code) and zip_code.len() What terminology do I need here so I can research the difference between what these things are? Continue reading...
