anchor.diff:  FROM ubuntu:14.04
   
  -# Ruby version
  +# Set ruby version.
   ENV RUBY_MAJOR 2.1
   ENV RUBY_MINOR 2.1.2
   
  
positive.code:     make install && \
      cd .. && \
      rm -r ruby-$RUBY_MINOR ruby-$RUBY_MINOR.tar.gz && \
      echo 'gem: --no-document' > /usr/local/etc/gemrc
  
  # Install bundler
  RUN gem install bundler
  
  # Copy the Gemfile and Gemfile.lock into the image.
  
negative.code:     nodejs \
      phantomjs
  
  # Install ruby.
  RUN curl -O http://ftp.ruby-lang.org/pub/ruby/$RUBY_MAJOR/ruby-$RUBY_MINOR.tar.gz && \
      tar -xzvf ruby-$RUBY_MINOR.tar.gz && \
      cd ruby-$RUBY_MINOR && \
  