code: def __call__(self, renderer):
      vl = [
          self._get_func(ax.get_tightbbox(renderer, False), ax.bbox)
          for ax in self._ax_list
      ]
      return max(vl)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import matplotlib.cbook
  from matplotlib.axes import Axes
label_desc: Use image node_id 6 for calling the GetExtentHelper obj's underlying member method code with example usage: obj.__call__(renderer) and returns: max