code: def __missing__(self, key):
      if self.default_factory is None:
          raise KeyError(key)
      self[key] = default = self.default_factory()
      return default
  
file_path: backtrader/backtrader/utils/ordereddefaultdict.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from collections import OrderedDict
  from .py3 import iteritems
label_desc: Use image node_id 2 for calling the OrderedDefaultdict obj's underlying member method code with example usage: obj.__missing__(key) and returns: default