anchor.diff:  
   RUN pip install csvkit
   
  -# Install R packages.
  -
  -COPY install_packages.R /tmp/build/
  -WORKDIR /tmp/build
  -RUN R CMD BATCH --no-save --no-restore install_packages.R
  -
   # Install PhantomJS.
   
   COPY install_phantomjs.sh /tmp/build/
  
positive.code: # Add package repositories.
  
  RUN apt-get install -y -q software-properties-common && \
      add-apt-repository 'deb http://cran.rstudio.com/bin/linux/ubuntu xenial/' && \
      add-apt-repository -y ppa:git-core/ppa && \
      add-apt-repository -y ppa:pi-rho/dev && \
      apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E084DAB9 && \
  
negative.code: COPY install_redis.sh /tmp/build/
  RUN /tmp/build/install_redis.sh
  
  # Install Emacs 26.1 from private Debian package
  # to work around https://github.com/docker/docker/issues/22801
  
  # RUN wget http://ftp.gnu.org/gnu/emacs/emacs-26.1.tar.gz && tar xzf emacs-26.1.tar.gz
  # WORKDIR /tmp/build/emacs-26.1
  # RUN ./configure --with-gnutls=no && make && make install
  #
  # To build private Debian package:
  # See https://github.com/jordansissel/fpm/wiki/PackageMakeInstall
  #
  # Install Ruby and FPM
  # make install DESTDIR=/tmp/installdir
  # fpm -s dir -t deb -C /tmp/installdir -n emacs26.1 -v 26.1-1 \
  #     -p emacs26.1_VERSION_ARCH.deb --description 'Emacs 26.1' usr
  
  RUN wget https://s3-us-west-1.amazonaws.com/royseto-public/dpkg/emacs26.1_26.1-1_amd64.deb \
    && dpkg -i /tmp/build/emacs26.1_26.1-1_amd64.deb
  
  # Install Python 2.7.11.
  
  