code: def saturation_mask(self, band, value=255):
          
          dn = self._get_band('b{}'.format(band))
          mask = self.mask()
          mask = where((dn == value) & (mask > 0), True, False)
  
          return mask
docs: Mask saturated pixels, 1 (True) is saturated.
          :param band: Image band with dn values, type: array
          :param value: Maximum (saturated) value, i.e. 255 for 8-bit data, type: int
          :return: boolean array