anchor.diff:  # Define default command.
   CMD ["bash"]
   
  +# Next: Git, bundle
  +RUN \
  +apt-get install git && apt-get install bundler
  +
   # Next: Volt
   RUN \
  -gem install volt
  +gem install volt \
  +volt new appname \
  +cd appname \
  +bundle
   
  -# Next: Git, bundle
  -RUN \
  -apt-get install git && apt-get install bundler \
  -cd appname
  -bundle install
   
  
positive.code: #
  # MongoDB Dockerfile
  #
  # https://github.com/dockerfile/mongodb
  #
  
  # Pull base image.
  FROM dockerfile/ubuntu
  
  
negative.code: EXPOSE 27017
  EXPOSE 28017
  
  # Install Ruby.
  RUN \
    apt-get update && \
  