def opcode_for_small_integer(small_int)
      raise ArgumentError, "small_int must not be nil" if !small_int
      return OP_0       if small_int == 0
      return OP_1NEGATE if small_int == -1
      if small_int >= 1 && small_int <= 16
        return OP_1 + (small_int - 1)
      end
      return OP_INVALIDOPCODE
    end
def opcode_for_small_integer(small_int)
      raise ArgumentError, "small_int must not be nil" if !small_int
      return OP_0       if small_int == 0
      return OP_1NEGATE if small_int == -1
      if small_int >= 1 && small_int <= 16
        return OP_1 + (small_int - 1)
      end
      return OP_INVALIDOPCODE
    end
Returns OP_1NEGATE, OP_0 .. OP_16 for ints from -1 to 16.
 Returns OP_INVALIDOPCODE for other ints.