docs: def print_treemap(self, format=None, output=sys.stdout, **kwargs):
          """
          Print the matrix for self's nodes.
  
          Args:
              format (str): output format (csv, json or text).
              output (file): file descriptor on which to write.
          """
          treemap = self.as_treemap()
          treemap.print(format=format, output=output, **kwargs)