code: def downgrade():
      if table_has_column("tables", "always_filter_main_dttm"):
          op.drop_column("tables", "always_filter_main_dttm")
  
file_path: superset/superset/migrations/versions/2023-09-06_13-18_317970b4400c_added_time_secondary_column_to_.py
imports: import sqlalchemy
  from alembic import op
  from sqlalchemy.ext.declarative import declarative_base
  from sqlalchemy.orm import Session
  from superset import db
  from superset.migrations.shared.utils import paginated_update, table_has_column
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types