<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def login(cls, email, password):
 """ Log in a user :param email: the user's email address :param password: the user's password :returns: (User, token) :raises: SocketError, CouchException """

        try:
            doc = yield cls.view.first(key=email, include_docs=True)
        except couch.NotFound:
            raise exceptions.Unauthorized('Unknown email address')

        user = cls(**doc['doc'])

        verified = user.verify_password(password)
        if not verified:
            raise exceptions.Unauthorized('Invalid password')

        token = yield Token.create(user)
        raise Return((user, token.id))