docs: def boundary(self):
          """ Get the image boundary
  
          Returns:
              A tupple composed by the westernmost_longitude,
              the westernmost_longitude, the minimum_latitude and
              the maximum_latitude.
  
          """
  
          return (int(self.WESTERNMOST_LONGITUDE),
                  int(self.EASTERNMOST_LONGITUDE),
                  int(self.MINIMUM_LATITUDE),
                  int(self.MAXIMUM_LATITUDE))