code: def recall(self, mode='all'):
          
          if mode == 'all':
              self._write('RDAT')
          elif mode == 'state':
              self._write('RSET')
          else:
              raise ValueError('Invalid recall mode.')
docs: Recalls from the file specified by :attr:`~SR850.filename`.
  
          :param mode: Specifies the recall mode.
  
              =======  ==================================================
              Value    Description
              =======  ==================================================
              'all'    Recalls the active display's data trace, the trace
                       definition and the instrument state.
              'state'  Recalls the instrument state.
              =======  ==================================================