def gen_all(self):
        """Generator of all borders"""

        borderfuncs = [
            self.get_b, self.get_r, self.get_t, self.get_l,
            self.get_tl, self.get_tr, self.get_rt, self.get_rb,
            self.get_br, self.get_bl, self.get_lb, self.get_lt,
        ]

        for borderfunc in borderfuncs:
            yield borderfunc()