def teardown_databases(self, old_config, **kwargs):
        for connection, old_name, destroy in old_config:
            if destroy:
                if self.parallel > 1:
                    for index in range(self.parallel):
                        connection.creation.destroy_test_db(
                            number=index + 1,
                            verbosity=self.verbosity,
                            keepdb=self.keepdb,
                        )
                connection.creation.destroy_test_db(old_name, self.verbosity, self.keepdb)
Returns the number of inter-community non-edges according to the
dataset/ETHPy150Open django/django/django/test/runner.py/DiscoverRunner.teardown_databases--crossover with--dataset/ETHPy150Open networkx/networkx/networkx/algorithms/community/quality.py/inter_community_non_edges