code: def cell_start(self, cell, cell_index=None, **kwargs):
          
          if self.log_output:
              ceel_num = cell_index + 1 if cell_index is not None else ''
              logger.info('Executing Cell {:-<40}'.format(ceel_num))
  
          cell.metadata.papermill['start_time'] = self.now().isoformat()
          cell.metadata.papermill["status"] = self.RUNNING
          cell.metadata.papermill['exception'] = False
  
          self.save()
docs: Set and save a cell's start state.
  
          Optionally called by engines during execution to initialize the
          metadata for a cell and save the notebook to the output path.