code: def db_url(tmp_path):
      db_file = tmp_path.joinpath("db_file")
      return f"sqlite:///{db_file}"
  
imports: import os
  import sqlite3
  import pytest
  import sqlalchemy
  from alembic import command
  from alembic.autogenerate import compare_metadata
  from alembic.migration import MigrationContext
  from alembic.script import ScriptDirectory
  import mlflow.db
  from mlflow.exceptions import MlflowException
  from mlflow.store.db.base_sql_model import Base
  from mlflow.store.db.utils import _get_alembic_config, _verify_schema
  from mlflow.store.tracking.dbmodels.initial_models import Base
  from mlflow.store.tracking.sqlalchemy_store import SqlAlchemyStore
  from tests.integration.utils import invoke_cli_runner
  from tests.store.dump_schema import dump_db_schema
label_desc: Use image node_id 3 for calling a global function with example usage: db_url(tmp_path) and returns: str, db_file