anchor.diff: +FROM selenium/node-firefox as firefox
   FROM derekadair/python-workflow:onbuild
   MAINTAINER Derek Adair "d@derekadair.com"
   # Add packages for firefox to list
  
positive.code: 
  # cleanup
  RUN apt-get clean
  
negative.code: 	apt-get install --force-yes -y \
          # Install fonts + firefox for headless testing in selenium
          xvfb \
          xfonts-100dpi \
          xfonts-75dpi \
          xfonts-scalable \
  