def clear(self, split):
for candidate_class in self.candidate_classes:<EOL><INDENT>logger.info(<EOL>f"<STR_LIT>"<EOL>)<EOL>self.session.query(Candidate).filter(<EOL>Candidate.type == candidate_class.__tablename__<EOL>).filter(Candidate.split == split).delete(synchronize_session="<STR_LIT>")<EOL><DEDENT>
Delete Candidates of each class initialized with the
        CandidateExtractor from given split the database.

        :param split: Which split to clear.
        :type split: int