anchor.diff:  # Octave Kernel
   # From arnau/docker-octave-notebook
   USER root
  -RUN apt-get update \
  - && apt-get install -y octave liboctave-dev \
  - && apt-get autoclean \
  - && apt-get clean \
  - && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
  +RUN apt-get update && \
  +    apt-get install -y octave liboctave-dev && \
  +    apt-get autoclean && \
  +    apt-get clean && \
  +    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
   
   USER $NB_USER
   
   #jupyter nbextension enable --py --sys-prefix widgetsnbextension
  -RUN pip install octave_kernel \
  - && python -m octave_kernel.install \
  - && conda install -y ipywidgets
  +RUN pip install octave_kernel && \
  +    python -m octave_kernel.install && \
  +    conda install -y ipywidgets
   
   
   ### Install Sage
  
positive.code: ENV SAGE_BIN_FILE sage-$SAGE_VER-Ubuntu_16.04-x86_64.tar.bz2
  ENV SAGE_ROOT /opt/sage/$SAGE_VER
  RUN mkdir -p $SAGE_ROOT && chown $NB_USER:users $SAGE_ROOT
  RUN apt-get update \
   && apt-get install -y --no-install-recommends bsdtar \
   && apt-get autoclean \
   && apt-get clean \
   && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
  
  USER $NB_USER
  WORKDIR $SAGE_ROOT
  RUN wget -nv http://mirrors.mit.edu/sage/linux/64bit/$SAGE_BIN_FILE
  RUN bsdtar -xjf $SAGE_BIN_FILE --strip-components=1
  RUN rm $SAGE_BIN_FILE
  
  USER root
  RUN ln -sf $SAGE_ROOT/sage /usr/bin/sage &&\
      ln -sf $SAGE_ROOT/sage /usr/bin/sagemath
  
  ADD ./add_sage/post.py $SAGE_ROOT/post.py
  
negative.code:     libtool libffi-dev make automake \
      libssl-dev libreadline-dev zlib1g-dev \
      git libzmq-dev autoconf pkg-config && \
      apt-get clean && \
      rm -rf /var/lib/apt/lists/*
  
  