func zip<Sequence1 : SequenceType, Sequence2 : SequenceType>(_: Sequence1, _: Sequence2) A sequence of pairs built out of two underlying sequences, where the elements of the ith pair are the ith elements of each underlying sequence. Declaration func zip<Sequence1 : SequenceType, Sequence2 : SequenceType>(sequence1: Sequence1, _ sequence2: Sequence2) -> Zip2Sequence<Sequence1, Sequence2>