code: def mysql(self):
      return exclusions.only_on(["mysql", "mariadb"])
  
imports: from sqlalchemy import exc
  from sqlalchemy import Index
  from sqlalchemy import text
  from alembic.testing import exclusions
  from alembic.testing.requirements import SuiteRequirements
  from alembic.util import compat
  from alembic.util import sqla_compat
label_desc: Use image node_id 29 for calling the DefaultRequirements obj's underlying member method code with example usage: obj.mysql() and returns: exclusions