code: def downgrade():
      ### commands auto generated by Alembic - please adjust! ###
      op.drop_table("dashboard_slices")
      op.drop_table("table_columns")
      op.drop_table("sql_metrics")
      op.drop_table("slices")
      op.drop_table("metrics")
      op.drop_table("columns")
      op.drop_table("tables")
      op.drop_table("datasources")
      op.drop_table("dbs")
      op.drop_table("dashboards")
      op.drop_table("clusters")
  
imports: import sqlalchemy
  from alembic import op
label_desc: Use image node_id 2 for calling a global function with example usage: downgrade() without return types