docstr: backend supports DEFERRABLE option in foreign keys
docstr_tok: ["backend","supports","DEFERRABLE","option","in","foreign","keys"]
code: def fk_deferrable(self):
      """backend supports DEFERRABLE option in foreign keys"""
      return exclusions.only_on(["postgresql", "oracle"])
  
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 12 for calling the DefaultRequirements obj's underlying member method code with example usage: obj.fk_deferrable() and returns: exclusions