Goal:
  
  x : byte
  y : byte
  z : byte
  H0 : BinInt.Z.lt (BinInt.Z.of_N (to_N y)) (BinInt.Z.of_N (to_N z))
  H : BinInt.Z.lt (BinInt.Z.of_N (to_N x)) (BinInt.Z.of_N (to_N y))
  cstr : BinInt.Z.le Z0 (BinInt.Z.of_N (to_N z))
  cstr0 : BinInt.Z.le Z0 (BinInt.Z.of_N (to_N y))
  cstr1 : BinInt.Z.le Z0 (BinInt.Z.of_N (to_N x))
  ============================
   (BinInt.Z.lt (BinInt.Z.of_N (to_N x)) (BinInt.Z.of_N (to_N z)))


DEBUG:Going to execute:
idtac