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Membership Tests
•The Contains and Find operations are used to determine whether an element is in the map.  Use Contains if all you need is a simple membership test. •Find returns a cursor as its result.  If the cursor object has the distinguished value No_Element (or equivalently, the predicate Has_Element returns False), then the search failed and the key is not in the map.  Otherwise, the cursor designates the key/element pair whose key matched.