code: def stop(self):
      super(WriterStringIO, self).stop()
      # Leave the file positioned at the beginning
      self.out.seek(0)
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import collections
  import io
  import itertools
  import sys
  import backtrader
  from backtrader.utils.py3 import map, with_metaclass, string_types, integer_types
label_desc: Use image node_id 3 for calling the WriterStringIO obj's underlying member method code with example usage: obj.stop() without return types