code: def ctrl(char):
          
          # Convert string to int... assuming any non-integer is a string.
          # TODO: Consider asserting a more rigorous test without falling back to past basestring.
          if not isinstance(char, int):
              char = ord(char.upper())
  
          # Only deal with the characters between '@' and '_'
          return char & 0x1f if 64 <= char <= 95 else None
docs: Calculate the control code for a given key.  For example, this converts
          "a" to 1 (which is the code for ctrl-a).
  
          :param char: The key to convert to a control code.
          :return: The control code as an integer or None if unknown.