### 1.11.9.1 Checking Session Existence or Validity

If for any reason you have an application which has run for a long time, it is possible that the session has expired since the session was originally created or loaded.

To check if a session is still valid use `manager.valid()`. The `valid()` method returns `True` if the session is valid, `False` otherwise and raises a `SessionError` if the session no longer exists.

It is also conceivably possible that the session has been cleaned up and no longer exists. To check if a session exists use `manager.exists()`. The `exists()` method returns `True` if the session exists, `False` otherwise but makes no comment on whether or not it is still valid or has expired.