title: Type hints for SQLAlchemy engine and session objects
body: <p>I'm trying to add type hints to my SQLAlchemy script:</p>
  
  <pre><code>connection_string: str = "sqlite:///:memory:"
  engine = create_engine(connection_string)
  session = Session(bind=engine)
  reveal_type(engine)
  reveal_type(session)
  </code></pre>
  
  <p>I've ran this script against <code>mypy</code> but both types comes back as <code>Any</code>. What type should the <code>engine</code> and <code>session</code> variable be?</p>