   let s = summer + winter + winter + summer
   let v = s.utf8
   for i in v.indices {
-    for j in i..<v.endIndex {      
+    for j in v.indices[i..<v.endIndex] {
       if let si = i.samePosition(in: s) {
         if let sj = j.samePosition(in: s) {
           expectEqual(s[si..<sj], String(v[i..<j])!)

    winter.utf16.indices.map {
      i16 in i16.samePosition(in: winter.utf8).map {
        i8 in (0..<3).map {
          winter.utf8[winter.utf8($0, stepsFrom: i8)]
        }
      } ?? []
    }, sameValue: ==)

        else {
          expectEmpty(u8i0a.samePosition(in: u16))
        }
        u8i0a = u8.index(1, stepsFrom: u8i0a)
      }

      expectEqual(u8i0a, u8i1) // We should be there now
