code: def _unescape_match(self, match):
          
          char = match.group(1)
          if char in self.ESCAPE_LOOKUP:
              return self.ESCAPE_LOOKUP[char]
          elif not char:
              raise KatcpSyntaxError("Escape slash at end of argument.")
          else:
              raise KatcpSyntaxError("Invalid escape character %r." % (char,))
docs: Given an re.Match, unescape the escape code it represents.