Fix: we don't know output type of deserializer
Fix: we don't know output type of deserializer

Be more explicit about the fact that we don't know the output of deserialized output

jupyter-widgets/ipywidgets,jupyter-widgets/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,jupyter-widgets/ipywidgets,jupyter-widgets/ipywidgets,ipython/ipywidgets,ipython/ipywidgets,ipython/ipywidgets