docs: def return_single_convert_numpy(self, object_id, converter, add_args=None):
          """
          Converts an object specified by the object_id into a numpy array and returns the array,
          the conversion is done by the 'converter' function
  
          Parameters
          ----------
          object_id : int, id of object in database
          converter : function, which takes the path of a data point and *args as parameters and returns a numpy array
          add_args : optional arguments for the converter (list/dictionary/tuple/whatever). if None, the
          converter should take only one input argument - the file path. default value: None
  
          Returns
          -------
          result : ndarray
          """
          return return_single_convert_numpy_base(self.dbpath, self.path_to_set, self._set_object, object_id, converter,
                                                  add_args)