code: def destroy_oaipmh_set(mapper, connection, community):
      
      from invenio_oaiserver.models import OAISet
      with db.session.begin_nested():
          oaiset = OAISet.query.filter_by(
              spec=community.oaiset_spec).one_or_none()
          if oaiset is None:
              raise Exception(
                  "OAISet for community {0} is missing".format(community.id))
          db.session.delete(oaiset)
docs: Signal for creating OAI-PMH sets during community creation.