Using the in Operator on Tuples, Sets, and Dictionaries

As with lists, the in operator can be applied to tuples and sets to check whether an item is a member of the collection:

When used on a dictionary, in checks whether a value is a key in the dictionary:

	>>> bird_to_observations = {'canada goose': 183, 'long-tailed jaeger': 71,
	... 'snow goose': 63, 'northern fulmar': 1}
	>>> 'snow goose' in bird_to_observations
	True
	>>> 183 in bird_to_observations
	False

Note that the values in the dictionary are ignored; the in operator only checks the keys.