def __setitem__(self, key, value, dict_setitem=dict.__setitem__):
<EOL>if key not in self:<EOL><INDENT>root = self.__root<EOL>last = root[<NUM_LIT:0>]<EOL>last[<NUM_LIT:1>] = root[<NUM_LIT:0>] = self.__map[key] = [last, root, key]<EOL><DEDENT>dict_setitem(self, key, value)<EOL>
od.__setitem__(i, y) <==> od[i]=y