code: def __report_result(self, report_type, level):
          
          if not self.__skip_this(level):
              level.report_type = report_type
              self.tree[report_type].add(level)
docs: Add a detected change to the reference-style result dictionary.
          report_type will be added to level.
          (We'll create the text-style report from there later.)
          :param report_type: A well defined string key describing the type of change.
                              Examples: "set_item_added", "values_changed"
          :param parent: A DiffLevel object describing the objects in question in their
                         before-change and after-change object structure.
  
          :rtype: None