code: def getPercentBlank(self):
          '''Print how many null cells are in the DEM - Quality measure'''
          blank = 0
          nonblank = 0
          for x in self.data.flat:
              if x == -99999.0:
                  blank = blank + 1
              else:
                  nonblank = nonblank + 1
  
          print ("Blank tiles =  ", blank, "out of ", (nonblank+blank)f getPercentBlank(self):
          '''Print how many null cells are in the DEM - Quality measure'''
          blank = 0
          nonblank = 0
          for x in self.data.flat:
              if x == -99999.0:
                  blank = blank + 1
              else:
                  nonblank = nonblank + 1
  
          print ("Blank tiles =  ", blank, "out of ", (nonblank+blank))
docs: Print how many null cells are in the DEM - Quality measure