code: def stop(self):
      t1 = datetime.datetime.utcnow()
      print("Duration:", t1 - self.t0)
  
file_path: backtrader/samples/tradingcalendar/tcal.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import argparse
  import datetime
  import backtrader
label_desc: Use image node_id 3 for calling the St obj's underlying member method code with example usage: obj.stop() without return types