Specification for session stores.
Removes the session associated with given session id from the store.
Parses the given cookie.
Returns a session id and the session contents. The session id is any value that can be used to identify the session by the store.
The session id may be nil in case the cookie does not identify any value in the store. The session contents must be a map.
Initializes the store.
The options returned from this function will be given