means the former will yield duplicate keys while the latter won't.
It also means ``len(list(iter(this_map)))`` could be different
than ``len(this_map.keys())``. ``len(this_map)`` will correspond
means the former will yield duplicate keys while the latter won't.
It also means ``len(list(iter(this_map)))`` could be different
than ``len(this_map.keys())``. ``len(this_map)`` will correspond