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Is there a short contains function for lists?

Given a list xs and a value item, how can I check whether xs contains item (i.e., if any of the elements of xs is equal to item)? Is there something like xs.contains(item)?


For performance considerations, see Fastest way to check if a value exists in a list.

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Answer

Use:

if my_item in some_list:
    ...

Also, inverse operation:

if my_item not in some_list:
    ...

It works fine for lists, tuples, sets and dicts (check keys).

Note that this is an O(n) operation in lists and tuples, but an O(1) operation in sets and dicts.

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