code: def nonetree(lb):
      """
      Make all elements in this tree none...  This signals not to do any more
      layout.
      """
      if lb is not None:
          if lb.parent is None:
              # Clear the solver.  Hopefully this garbage collects.
              lb.solver.reset()
              nonechildren(lb)
          else:
              nonetree(lb.parent)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import itertools
  import kiwisolver
  import logging
  import numpy
  import warnings
  import matplotlib
label_desc: Use image node_id 20 for calling a global function with example usage: nonetree(lb) without return types