code: def _get_relationship_cell_val(self, obj, column):
          
          val = ""
          key = column['key']
          related_key = column.get('related_key', None)
  
          related_obj = getattr(obj, key, None)
  
          if related_obj is None:
              return ""
  
          if column['__col__'].uselist:  # OneToMany
              # We know how to retrieve a value from the related objects
              if related_key is not None:
                  # Only the related object of the given index
                  if column.get('index') is not None:
                      if len(related_obj) > column['index']:
                          rel_obj = related_obj[column['index']]
                          val = self._get_formatted_val(
                              rel_obj,
                              related_key,
                              column,
                          )
                  # We join all the related objects val
                  else:
                      _vals = []
                      for rel_obj in related_obj:
                          _vals.append(
                              self._get_formatted_val(
                                  rel_obj,
                                  related_key,
                                  column,
                              )
                          )
                      val = '\n'.join(_vals)
          else:  # Many to One
              if related_key is not None:
                  val = self._get_formatted_val(related_obj, related_key, column)
  
          return val
docs: Return the value to insert in a relationship cell