Return the entries written by the given usernames
        When multiple tags are provided, they operate as "OR" query.

def authors(self, *usernames):
        """
        Return the entries written by the given usernames
        When multiple tags are provided, they operate as "OR" query.
        """
        if len(usernames) == 1:
            return self.filter(**{"author__{}".format(User.USERNAME_FIELD): usernames[0]})
        else:
            return self.filter(**{"author__{}__in".format(User.USERNAME_FIELD): usernames})