'Returns whether the data in storage for the given key is
already up-to-date with the version in the given modulestore.'

def is_up_to_date(self, root_block_usage_key, modulestore):

    if _is_storage_backing_enabled():
        try:
            bs_model = self._get_model(root_block_usage_key)
            root_block = modulestore.get_item(root_block_usage_key)
            return (self._version_data_of_model(bs_model) == self._version_data_of_block(root_block))
        except BlockStructureNotFound:
            pass
    return False
