code: def refresh_all(self):
      if self.web_sockets:
          diff = self.canvas.get_diff_image()
          if diff is not None:
              for s in self.web_sockets:
                  s.send_binary(diff)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import six
  import datetime
  import io
  import json
  import os
  import warnings
  import numpy
  import tornado
  from matplotlib.backends import backend_agg
  from matplotlib.backend_bases import _Backend
  from matplotlib import backend_bases
  from matplotlib import _png
label_desc: Use image node_id 9 for calling the FigureManagerWebAgg obj's underlying member method code with example usage: obj.refresh_all() without return types