<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _metadata_is_invalid(cls, fact):
 """Filters out blank nodes since the SPARQLUpdateStore does not support them. """

        return (MetadataCache._metadata_is_invalid(fact)
                or any(isinstance(token, BNode) for token in fact))