1class Mapping:
2 def __init__(self, iterable):
3 self.items_list = []
4 self.__update(iterable)
5
6 def update(self, iterable):
7 for item in iterable:
8 self.items_list.append(item)
9
10 __update = update # private copy of original update() method
11
12class MappingSubclass(Mapping):
13 # MappingSubclass inherits methods and attributes from Mapping
14 def update(self, keys, values):
15 # provides new signature for update()
16 # but does not break __init__()
17 for item in zip(keys, values):
18 self.items_list.append(item)
19