Saves the token dict in the store
        :return bool: Success / Failure

def save_token(self):
        """
        Saves the token dict in the store
        :return bool: Success / Failure
        """
        if self.token is None:
            raise ValueError('You have to set the "token" first.')

        try:
            # set token will overwrite previous data
            self.doc_ref.set({
                self.field_name: self.serializer.dumps(self.token)
            })
        except Exception as e:
            log.error('Token could not be saved: {}'.format(str(e)))
            return False

        return True