anchor.diff:  
   RUN python3 -m pip install jupyterlab
   RUN python3 -m pip install ipywidgets
  +RUN python3 -m pip install pyspark
   
   RUN pip3 install jupyter-tensorboard
   
  
positive.code: #ENV DEBIAN_FRONTEND noninteractive 
  ENV INITRD No
  #ENV LANG en_US.UTF-8
  ENV JUPYTER_VERSION 999999 
  
  LABEL Name="Jupyter for CRE" \
        CRE=$CRE_VERSION \ 
  
negative.code: #
  # https://jupyterlab.readthedocs.io/en/stable/user/jupyterhub.html
  # https://nbconvert.readthedocs.io/en/latest/install.html#installing-nbconvert
  
  # https://www.kdnuggets.com/2020/07/apache-spark-cluster-docker.html
  
  # Jupyter Hub Dockerfile 
  #
  