gistfile1.txt

DB_ENGINE = <have your engine available here>

@contextmanager
def get_session():
    """Provide a transactional scope around a series of operations."""
    session = sqlalchemy.orm.sessionmaker(bind=DB_ENGINE)()
    try:
        yield session
        session.commit()
    except:
        session.rollback()
        raise
    finally:
        session.close()
        
with get_session() as db_session:
  # Do some DB stuff in you nice fancy db_session
  pass