docs: def get_multifile_object_child_location(self, parent_item_prefix: str, child_name: str) -> str:
          """
          Implementation of the parent abstract method.
          In this mode the attribute is a file inside the parent object folder
  
          :param parent_item_prefix: the absolute file prefix of the parent item.
          :return: the file prefix for this attribute
          """
          check_var(parent_item_prefix, var_types=str, var_name='parent_item_prefix')
          check_var(child_name, var_types=str, var_name='item_name')
  
          # assert that folder_path is a folder
          if not isdir(parent_item_prefix):
              raise ValueError(
                  'Cannot get attribute item in non-flat mode, parent item path is not a folder : ' + parent_item_prefix)
          return join(parent_item_prefix, child_name)