code: def prenext(self):
      self.next(frompre=True)
  
file_path: backtrader/samples/vctest/vctest.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import datetime
  import backtrader
  from backtrader.utils import flushfile
  from backtrader.utils.py3 import string_types
label_desc: Use image node_id 6 for calling the TestStrategy obj's underlying member method code with example usage: obj.prenext() without return types