code: def prenext(self):
      self.counter += 1
      print("prenext len %d - counter %d" % (len(self), self.counter))
  
file_path: backtrader/samples/data-replay/data-replay.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import backtrader
  import backtrader.feeds
  import backtrader.indicators
label_desc: Use image node_id 3 for calling the SMAStrategy obj's underlying member method code with example usage: obj.prenext() without return types