anchor.diff:  # same for py3, and install juptyerhub in the py3 env
   RUN source activate py3 && ipython kernel install
   
  -RUN conda update -n base conda -y && conda install -c conda-forge jupyterhub -y
  +RUN conda install -c conda-forge jupyterhub -y
   
   # ipywidgets: https://github.com/ipython/ipywidgets
   RUN jupyter nbextension enable --py --sys-prefix widgetsnbextension
  
positive.code: # https://repo.continuum.io/archive
  ENV CONDA_VER 5.3.0
  
  RUN wget https://repo.continuum.io/archive/Anaconda3-$CONDA_VER-Linux-x86_64.sh \
  	&& bash Anaconda3-$CONDA_VER-Linux-x86_64.sh -b -p /usr/local/conda/anaconda3 \
  	&& rm -f Anaconda3-$CONDA_VER-Linux-x86_64.sh
  
  ENV PATH $PATH:/usr/local/conda/anaconda3/bin
  
  # Install py2 and py3 envs, and registers jupyterhub kernels
  # https://github.com/jupyter/jupyter/issues/71
  
negative.code: 
  # GIT - https://git-scm.com/
  # http://tecadmin.net/install-git-2-0-on-centos-rhel-fedora/#
  ENV GIT_VER 2.19.1
  
  RUN wget https://www.kernel.org/pub/software/scm/git/git-$GIT_VER.tar.gz \
  	&& tar xf git-$GIT_VER.tar.gz && cd git-$GIT_VER \
  