Checks if the current band is filled.

        The size of the current band should be equal to s_max_1

def _cur_band_filled(self):
        """Checks if the current band is filled.

        The size of the current band should be equal to s_max_1"""

        cur_band = self._hyperbands[self._state["band_idx"]]
        return len(cur_band) == self._s_max_1