anchor.diff:  # Builds the python-minecraft-student Docker image. Each student will
   # get their own container built from this image.
   
  -FROM ubuntu:14.04
  +FROM phusion/baseimage:0.9.16
   MAINTAINER Mike McCallister <mike@mccllstr.com>
   
   # ----------------------------------------------------------------------------
  
positive.code:         openssl \
          psmisc \
          python-imaging \
          python-pygame \
          supervisor \
          tmux \
          unzip \
          zip \
      && apt-get clean
  
  
  # ----------------------------------------------------------------------------
  
negative.code: # advantage of its cache, which greatly speeds up subsequent builds.
  
  RUN apt-get update \
      && apt-get install --no-install-recommends --no-install-suggests -y \
          apg \
          curl \
          git-core \
  