code: def next(self):
      txt = list()
      txt.append("%04d" % len(self.data0))
      txt.append("{}".format(self.data0._dataname))
      # Internal knowledge ... current expiration in use is in _d
      txt.append("{}".format(self.data0._d._dataname))
      txt.append("{}".format(self.data.datetime.date()))
      txt.append("{}".format(self.data.datetime.date().strftime("%a")))
      txt.append("{}".format(self.data.open[0]))
      txt.append("{}".format(self.data.high[0]))
      txt.append("{}".format(self.data.low[0]))
      txt.append("{}".format(self.data.close[0]))
      txt.append("{}".format(self.data.volume[0]))
      txt.append("{}".format(self.data.openinterest[0]))
      print(", ".join(txt))
  
file_path: backtrader/samples/rollover/rollover.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import bisect
  import calendar
  import datetime
  import backtrader
label_desc: Use image node_id 2 for calling the TheStrategy obj's underlying member method code with example usage: obj.next() without return types