code: def is_erased(self, d):
          
          erasedByte = self.erased_byte_value
          for b in d:
              if b != erasedByte:
                  return False
          return True
docs: ! @brief Helper method to check if a block of data is erased.
          @param self
          @param d List of data or bytearray.
          @retval True The contents of d all match the erased byte value for this flash region.
          @retval False At least one byte in d did not match the erased byte value.