def _reload_doc(
        cls, collection_name, sample_id, hard=False, include_frames=False
    ):
        """Reloads the backing document for the given sample if it is
        in-memory.
        """
        if collection_name not in cls._instances:
            return

        sample = cls._instances[collection_name].get(str(sample_id), None)
        if sample is not None:
            sample.reload(hard=hard, include_frames=include_frames)
Reloads the backing document for the given sample if it is
        in-memory.
        
fiftyone/core/singletons.py