code: def _escapify(label):
      
      text = ''
      for c in label:
          if c in _escaped:
              text += '\\' + c
          elif ord(c) > 0x20 and ord(c) < 0x7F:
              text += c
          else:
              text += '\\%03d' % ord(c)
      return text
docs: Escape the characters in label which need it.
      @returns: the escaped string
      @rtype: string