code: def missing_datetimes(self, finite_datetimes):
          
          return [d for d in finite_datetimes if not self._instantiate_task_cls(self.datetime_to_parameter(d)).complete()]
docs: Override in subclasses to do bulk checks.
  
          Returns a sorted list.
  
          This is a conservative base implementation that brutally checks completeness, instance by instance.
  
          Inadvisable as it may be slow.