anchor.diff:  
   RUN apt-get update && \
       apt-get install -y wget software-properties-common apt-transport-https && \
  -    add-apt-repository ppa:brightbox/ruby-ng && \
       echo "deb https://deb.nodesource.com/$NODE_VERSION $DISTRO main" >/etc/apt/sources.list.d/nodesource.list && \
       echo "deb https://packages.erlang-solutions.com/ubuntu $DISTRO contrib" >/etc/apt/sources.list.d/esl.list && \
       wget --quiet -O - https://deb.nodesource.com/gpgkey/nodesource.gpg.key | apt-key add - && \
  
positive.code: #   libfontconfig1 for PhantomJS
  #   ttf-bitstream-vera for a2png
  #   libpng16-16 for pngquant
  
  # install Bundler and SASS
  
  RUN gem install bundler sass
  
  # install Hex and Rebar
  
  
negative.code:       build-essential \
        elixir=1.6.3-1 \
        esl-erlang=1:20.1 \
        libfontconfig1 \
        libpng16-16 \
        nodejs \
        ttf-bitstream-vera \
        tzdata
  
  