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>>> d = {"first_name": "Cosmo", "last_name": "Kramer"}
>>> keys = d.keys()
# dict_keys inherits from the Set abstract base class
>>> isinstance(keys, collections.abc.Set)
True
# Check that the set containing "first_name" is a subset of keys
>>> {"first_name"} < keys
True
# Unions also work
>>> {"age"} | keys
{'age', 'first_name', 'last_name'}
# As do intersections
>>> {"last_name", "address", "website"} & keys
{'last_name'}

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Python Dictionary Tricks: Keys are set-like and support most set operations

Because keys must be hashable and unique in a dictionary, they act like sets. You can use most set-like operations on them, and because they’re views, they always reflect the actual contents of the underlying dictionary. But because it’s a view it is read-only. Values, however, are not set-like; they can contain complex unhashable objects and may contain duplicates.

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