code: def ExpandArg(self, **_):
      
      # This function is called when we see close ) and the stack depth has to
      # exactly match the number of (.
      if len(self.stack) <= 1:
        raise lexer.ParseError(
            "Unbalanced parenthesis: Can not expand '%s'" % self.processed_buffer)
  
      # This is the full parameter name: e.g. Logging.path
      parameter_name = self.stack.pop(-1)
      if "." not in parameter_name:
        parameter_name = "%s.%s" % (self.default_section, parameter_name)
  
      final_value = self.config.Get(parameter_name, context=self.context)
      if final_value is None:
        final_value = ""
  
      type_info_obj = (
          self.config.FindTypeInfo(parameter_name) or type_info.String())
  
      # Encode the interpolated string according to its type.
      self.stack[-1] += type_info_obj.ToString(final_value)
docs: Expand the args as a section.parameter from the config.