code: def downgrade():
      Base.metadata.drop_all(bind=op.get_bind(), tables=new_tables)
  
imports: import json
  import os
  from datetime import datetime
  from typing import Optional, Union
  from uuid import uuid4
  import sqlalchemy
  from alembic import op
  from sqlalchemy import select
  from sqlalchemy.ext.declarative import declarative_base, declared_attr
  from sqlalchemy.orm import backref, relationship, Session
  from sqlalchemy.schema import UniqueConstraint
  from sqlalchemy.sql import functions
  from sqlalchemy.sql.expression import and_, or_
  from sqlalchemy_utils import UUIDType
  from superset.connectors.sqla.models import ADDITIVE_METRIC_TYPES_LOWER
  from superset.connectors.sqla.utils import get_dialect_name, get_identifier_quoter
  from superset.extensions import encrypted_field_factory
  from superset.migrations.shared.utils import assign_uuids
  from superset.sql_parse import extract_table_references, Table
  from superset.utils.core import MediumText
label_desc: Use image node_id 11 for calling a global function with example usage: downgrade() without return types