code: def start_workunit(self, workunit):
      
      if not self.is_under_main_root(workunit):
        return
  
      label_format = self._get_label_format(workunit)
  
      if label_format == LabelFormat.FULL:
        if not WorkUnitLabel.SUPPRESS_LABEL in workunit.labels:
          self._emit_indented_workunit_label(workunit)
        # Start output on a new line.
        tool_output_format = self._get_tool_output_format(workunit)
        if tool_output_format == ToolOutputFormat.INDENT:
          self.emit(self._prefix(workunit, '\n'))
        elif tool_output_format == ToolOutputFormat.UNINDENTED:
          self.emit('\n')
      elif label_format == LabelFormat.DOT:
        self.emit('.')
  
      self.flush()
docs: Implementation of Reporter callback.