code: def nonfirst_authors(self, key, value):
      
      field_700 = self.get('700__', [])
      field_701 = self.get('701__', [])
  
      is_supervisor = any(el.lower().startswith('dir') for el in force_list(value.get('e', '')))
      if is_supervisor:
          field_701.append(_converted_author(value))
      else:
          field_700.append(_converted_author(value))
  
      self['701__'] = field_701
      return field_700
docs: Populate ``700`` MARC field.
  
      Also populates the ``701`` MARC field through side-effects.