method
contains

bool contains(
Object object
)

Returns true if the collection contains an element equal to [element].

This operation will check each element in order for being equal to [element], unless it has a more efficient way to find an element equal to [element].

The equality used to determine whether [element] is equal to an element of the iterable defaults to the [Object.operator==] of the element.

Some types of iterable may have a different equality used for its elements. For example, a [Set] may have a custom equality (see [Set.identical]) that its contains uses. Likewise the Iterable returned by a [Map.keys] call should use the same equality that the Map uses for keys.