docs: def _NewMatchSection(self, val):
      """Create a new configuration section for each match clause.
  
      Each match clause is added to the main config, and the criterion that will
      trigger the match is recorded, as is the configuration.
  
      Args:
        val: The value following the 'match' keyword.
      """
      section = {"criterion": val, "config": {}}
      self.matches.append(section)
      # Now add configuration items to config section of the match block.
      self.section = section["config"]
      # Switch to a match-specific processor on a new match_block.
      self.processor = self._ParseMatchGrp