anchor.diff:  
   # Exporting HTML requires either of Node.JS or Pandoc.
   RUN apt-get install -y nodejs
  -RUN apt-get clean
   
   # Use `pip` to make sure latest versions.
   RUN pip3 install pyzmq
  
positive.code: RUN pip3 install Sphinx
  RUN pip3 install ipython[notebook]
  
  # For IPython Notebook to share resources with host.
  EXPOSE 8888
  VOLUME ["/notebook"]
  
negative.code: FROM ubuntu:14.04
  MAINTAINER Itoshi NIKAIDO "dritoshi@gmail.com"
  
  RUN locale-gen en_US.UTF-8
  RUN update-locale LANG=en_US.UTF-8
  ENV LC_ALL C
  ENV LC_ALL en_US.UTF-8
  
  # apt-get
  ENV DEBIAN_FRONTEND noninteractive
  RUN echo "deb http://jp.archive.ubuntu.com/ubuntu/ trusty main restricted\n\
  deb-src http://jp.archive.ubuntu.com/ubuntu/ trusty main restricted\n\
  deb http://jp.archive.ubuntu.com/ubuntu/ trusty-updates main restricted\n\
  deb-src http://jp.archive.ubuntu.com/ubuntu/ trusty-updates main restricted\n\
  deb http://jp.archive.ubuntu.com/ubuntu/ trusty universe\n\
  deb-src http://jp.archive.ubuntu.com/ubuntu/ trusty universe\n\
  deb http://jp.archive.ubuntu.com/ubuntu/ trusty-updates universe\n\
  deb-src http://jp.archive.ubuntu.com/ubuntu/ trusty-updates universe\n\
  deb http://jp.archive.ubuntu.com/ubuntu/ trusty multiverse\n\
  deb-src http://jp.archive.ubuntu.com/ubuntu/ trusty multiverse\n\
  deb http://jp.archive.ubuntu.com/ubuntu/ trusty-updates multiverse\n\
  deb-src http://jp.archive.ubuntu.com/ubuntu/ trusty-updates multiverse\n\
  deb http://jp.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse\n\
  deb-src http://jp.archive.ubuntu.com/ubuntu/ trusty-backports main restricted universe multiverse\n\
  deb http://security.ubuntu.com/ubuntu trusty-security main restricted\n\
  deb-src http://security.ubuntu.com/ubuntu trusty-security main restricted\n\
  deb http://security.ubuntu.com/ubuntu trusty-security universe\n\
  deb-src http://security.ubuntu.com/ubuntu trusty-security universe\n\
  deb http://security.ubuntu.com/ubuntu trusty-security multiverse\n\
  deb-src http://security.ubuntu.com/ubuntu trusty-security multiverse\n"> /etc/apt/sources.list
  
  # CRAN
  RUN echo "deb http://cran.ism.ac.jp/bin/linux/ubuntu trusty/" >> /etc/apt/sources.list
  RUN apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E084DAB9
  
  RUN apt-get update
  RUN apt-get upgrade -y
  