'Returns the amount of unread messages for this user
:param user:
A Django :class:`User`
:return:
An integer with the amount of unread messages.'

def count_unread_messages_for(self, user):

    unread_total = self.filter(user=user, read_at__isnull=True, deleted_at__isnull=True).count()
    return unread_total
