`eachPair` without `AnySequence`

each-pair-without-any-sequence.md

eachPair without AnySequence

extension Sequence where Self.SubSequence: Sequence {
  func eachPair() -> Zip2Sequence<Self, Self.SubSequence> {
    return zip(self, self.dropFirst())
  }
}

(1...10).eachPair().forEach { print($0) }

(1, 2)
(2, 3)
(3, 4)
(4, 5)
(5, 6)
(6, 7)
(7, 8)
(8, 9)
(9, 10)