anchor.diff:                  patch \
                   xz-utils \
                   zlib1g-dev \
  +                build-essential \
                   git \
   		libasound2 \
    		python-ply \
  
positive.code: COPY xvfb-run /usr/local/bin/
  RUN chmod +x /usr/local/bin/xvfb-run
  
  # cleanup
  RUN apt-get clean
  RUN rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
  
negative.code:         && rm -rf /var/lib/apt/lists/*
  
  #install fake X server
  RUN wget http://ftp.us.debian.org/debian/pool/main/x/xorg-server/xvfb_1.18.1-1_amd64.deb
  RUN wget http://ftp.us.debian.org/debian/pool/main/libx/libxfont/libxfont1_1.5.1-1_amd64.deb
  RUN wget http://ftp.us.debian.org/debian/pool/main/libf/libfontenc/libfontenc1_1.1.2-1+b2_amd64.deb
  RUN wget http://ftp.us.debian.org/debian/pool/main/x/xkeyboard-config/xkb-data_2.12-1_all.deb
  