Part of Optional.swift

gistfile1.txt

public enum Optional<Wrapped>: ExpressibleByNilLiteral {
  case none
  case some(Wrapped)

  public init(_ some: Wrapped) { self = .some(some) }
  public init(nilLiteral: ()) {
    self = .none
  }

   @inlinable
  public static func ==(lhs: Wrapped?, rhs: Wrapped?) -> Bool {
    switch (lhs, rhs) {
    case let (l?, r?):
      return l == r
    case (nil, nil):
      return true
    default:
      return false
    }
  }
  .....
}