code: def _set_band_and_valid_mask(self):
          
          data = np.asarray(self.ogc_request.get_data())
          self.bands = data[..., :-1]
          self.valid_data = (data[..., -1] == 1.0).astype(np.bool)
docs: Downloads band data and valid mask. Sets parameters self.bands, self.valid_data