每当我尝试通过烧瓶连接我的psql时，都会出现错误提示

Question

flask.cli.NoAppException

NoAppException: While importing "application", an ImportError was raised:

Traceback (most recent call last):
  File "/home/shwet/.local/lib/python2.7/site-packages/flask/cli.py", line 240, in locate_app
    __import__(module_name)
  File "/home/shwet/sr/WebDevlopment/lecture3/project1/application.py", line 17, in <module>
    Session(app)
  File "/home/shwet/.local/lib/python2.7/site-packages/flask_session/__init__.py", line 54, in __init__
    self.init_app(app)
  File "/home/shwet/.local/lib/python2.7/site-packages/flask_session/__init__.py", line 61, in init_app
    app.session_interface = self._get_interface(app)
  File "/home/shwet/.local/lib/python2.7/site-packages/flask_session/__init__.py", line 93, in _get_interface
    config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])
  File "/home/shwet/.local/lib/python2.7/site-packages/flask_session/sessions.py", line 313, in __init__
    from werkzeug.contrib.cache import FileSystemCache
ImportError: No module named contrib.cache