Generic Instance Method

# starts(with:)

Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.

## Parameters

`possiblePrefix`

A sequence to compare to this sequence.

## Return Value

`true` if the initial elements of the sequence are the same as the elements of `possiblePrefix`; otherwise, `false`. If `possiblePrefix` has no elements, the return value is `true`.

## Discussion

This example tests whether one countable range begins with the elements of another countable range.

Passing a sequence with no elements or an empty collection as `possiblePrefix` always results in `true`.

Complexity: O(m), where m is the lesser of the length of the sequence and the length of `possiblePrefix`.

### Testing Set Membership

`func contains(IndexSet.Element) -> Bool`

Returns `true` if `self` contains `integer`.

`func contains(integersIn: IndexSet) -> Bool`

Returns `true` if `self` contains all of the integers in `indexSet`.

`func contains(integersIn: Range<IndexSet.Element>) -> Bool`

Returns `true` if `self` contains all of the integers in `range`.

`func contains(where: (Int) -> Bool) -> Bool`

Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.

`func intersects(integersIn: Range<IndexSet.Element>) -> Bool`

Returns `true` if `self` intersects any of the integers in `range`.

`func isDisjoint(with: IndexSet) -> Bool`

Returns a Boolean value that indicates whether the set has no members in common with the given set.

`func isStrictSubset(of: IndexSet) -> Bool`

Returns a Boolean value that indicates whether this set is a strict subset of the given set.

`func isStrictSuperset(of: IndexSet) -> Bool`

Returns a Boolean value that indicates whether this set is a strict superset of the given set.

`func isSubset(of: IndexSet) -> Bool`

Returns a Boolean value that indicates whether the set is a subset of another set.

`func isSuperset(of: IndexSet) -> Bool`

Returns a Boolean value that indicates whether the set is a superset of the given set.