code: def init_db(self, db_uri):
      self.db_uri = db_uri
      self.db_type = extract_db_type_from_uri(db_uri)
      self.engine = create_sqlalchemy_engine_with_retry(db_uri)
      dbutils.migrate_if_needed(self.engine, "head")
      SessionMaker = sessionmaker(bind=self.engine)
      self.ManagedSessionMaker = _get_managed_session_maker(
          SessionMaker, self.db_type
      )
  
imports: from typing import List, Optional
  from sqlalchemy.exc import IntegrityError, MultipleResultsFound, NoResultFound
  from sqlalchemy.orm import sessionmaker
  from werkzeug.security import check_password_hash, generate_password_hash
  from mlflow.exceptions import MlflowException
  from mlflow.protos.databricks_pb2 import INVALID_STATE, RESOURCE_ALREADY_EXISTS, RESOURCE_DOES_NOT_EXIST
  from mlflow.server.auth.db import utils
  from mlflow.server.auth.db.models import SqlExperimentPermission, SqlRegisteredModelPermission, SqlUser
  from mlflow.server.auth.entities import ExperimentPermission, RegisteredModelPermission, User
  from mlflow.server.auth.permissions import _validate_permission
  from mlflow.store.db.utils import _get_managed_session_maker, create_sqlalchemy_engine_with_retry
  from mlflow.utils.uri import extract_db_type_from_uri
  from mlflow.utils.validation import _validate_username
label_desc: Use image node_id 1 for calling the SqlAlchemyStore obj's underlying member method code with example usage: obj.init_db(db_uri) without return types