docs: def getattr_path(obj, path):
      """
      Get an attribute path, as defined by a string separated by '__'.
      getattr_path(foo, 'a__b__c') is roughly equivalent to foo.a.b.c but
      will short circuit to return None if something on the path is None.
      """
      path = path.split('__')
      for name in path:
          obj = getattr(obj, name)
          if obj is None:
              return None
      return obj