Generic Instance Method

# starts(with:by:)

Returns a Boolean value indicating whether the initial elements of the sequence are equivalent to the elements in another sequence, using the given predicate as the equivalence test.

## Parameters

`possiblePrefix`

A sequence to compare to this sequence.

`areEquivalent`

A predicate that returns `true` if its two arguments are equivalent; otherwise, `false`.

## Return Value

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

## Discussion

The predicate must be a equivalence relation over the elements. That is, for any elements `a`, `b`, and `c`, the following conditions must hold:

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

• `areEquivalent(a, a)` is always `true`. (Reflexivity)

• `areEquivalent(a, b)` implies `areEquivalent(b, a)`. (Symmetry)

• If `areEquivalent(a, b)` and `areEquivalent(b, c)` are both `true`, then `areEquivalent(a, c)` is also `true`. (Transitivity)

### Comparing Characters

`func elementsEqual<OtherSequence>(OtherSequence) -> Bool`

Returns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.

`func elementsEqual<OtherSequence>(OtherSequence, by: (Character, OtherSequence.Element) -> Bool) -> Bool`

Returns a Boolean value indicating whether this sequence and another sequence contain equivalent elements in the same order, using the given predicate as the equivalence test.

`func starts<PossiblePrefix>(with: PossiblePrefix) -> Bool`

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

`func lexicographicallyPrecedes<OtherSequence>(OtherSequence) -> Bool`

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (`<`) to compare elements.

`func lexicographicallyPrecedes<OtherSequence>(OtherSequence, by: (Character, Character) -> Bool) -> Bool`

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.