anchor.diff:  
   # Python
   RUN apt-get install -y python3 python3-dev python3-setuptools ipython3 \
  -    python3-scipy python python-dev python-pip python-setuptools ipython \
  +    python3-scipy python3-pip python python-dev python-pip python-setuptools ipython \
       python-scipy python-matplotlib python-virtualenv virtualenvwrapper
   
   # Julia
  
positive.code: # RUN ...
  RUN apt-get install -y pylint zip
  RUN sudo a2enmod rewrite
  RUN curl -sS https://getcomposer.org/installer | php
  RUN mv composer.phar /usr/bin/composer
  RUN apt-get install -y php5-mcrypt
  RUN apt-get install -y python3-pip
  RUN sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10 && \
      echo "deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen" | sudo tee /etc/apt/sources.list.d/mongodb.list && \
      sudo apt-get update && \
      sudo apt-get install -y mongodb-org
  
  # setup the system
  RUN echo -n "" > /etc/motd && \
  
negative.code:     bash -c "shopt -s dotglob && cp -a /tmp/homedir/* /home/ubuntu" && \
      rm -rf /tmp/homedir && \
      echo "Configure mongodb" && \
      sudo sed -i 's/journal=true/journal=false\nnojournal=true\nsmallfiles=true/' /etc/mongod.conf && \
      echo "Configure apache2" && \
      sudo sed -i 's/Listen 80\b/Listen 8080/' /etc/apache2/ports.conf && \
      ln -s /etc/apache2/sites-available/001-cloud9.conf /etc/apache2/sites-enabled && \
  