code: def generate_filename(self, directory=os.getcwd(), prefix='tile',
                            format='png', path=True):
          
          filename = prefix + '_{col:02d}_{row:02d}.{ext}'.format(
                        col=self.column, row=self.row, ext=format.lower().replace('jpeg', 'jpg'))
          if not path:
              return filename
          return os.path.join(directory, filename)
docs: Construct and return a filename for this tile.