New submission from ThiefMaster:
d = {'1': '2'}
{'1'} d.keys()
False
{'1'} set(d.values())
False
{'1'} d.values()
Traceback (most recent call last):
File stdin, line 1, in module
TypeError: unorderable types: set() dict_values()
Same for e.g. the `-` operator.
Since dict_keys acts
R. David Murray added the comment:
values cannot be a set, since unlike keys it may contain unhashable objects.
It would be...really strange and contrary to Python's philosophy to have the
validity of an operation depend on the specific data values in a structure
rather than its type.
