code: def _start(self):
      self.start()
  
file_path: backtrader/backtrader/observer.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from .lineiterator import LineIterator, ObserverBase, StrategyBase
  from backtrader.utils.py3 import with_metaclass
label_desc: Use image node_id 3 for calling the Observer obj's underlying member method code with example usage: obj._start() without return types