code: def downgrade():
      """
      It's impossible to downgrade this migration.
      """
      pass
  
file_path: superset/superset/migrations/versions/2021-02-04_09-34_070c043f2fdb_add_granularity_to_charts_where_missing.py
imports: import json
  from alembic import op
  from sqlalchemy import and_, Boolean, Column, Integer, String, Text
  from sqlalchemy.ext.declarative import declarative_base
  from superset import db
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types