code: def add_squashed_change(self, path, data):
          # type: (List[str], Any) -> None
          
          assert self._squashed_count, "Called while not squashing changes"
          self._squashed_changes.append([path[1:], data])
docs: Register a squashed change to a particular path
  
          Args:
              path (list): The path of what has changed, relative from Block
              data (object): The new data