code: def start(self):
      self.broker.setcommission(
          commission=2.0, mult=10.0, margin=1000.0
      )
      self.tstart = time_clock()
      self.buy_create_idx = itertools.count()
  
file_path: backtrader/tests/test_strategy_optimized.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import itertools
  import time
  import testcommon
  from backtrader.utils.py3 import range
  import backtrader
  import backtrader.indicators
label_desc: Use image node_id 3 for calling the TestStrategy obj's underlying member method code with example usage: obj.start() without return types