code: def get_line_str(self):
          
          if self.from_string:
              return ' '.join([s for s in [self.merge_marker_str,
                                           self._datetime_str,
                                           self._line_str] if s])
          else:
              return ' '.join([s for s in [self._datetime_str,
                                           self._line_str] if s])
docs: Return line_str depending on source, logfile or system.profile.