anchor.diff:  ENV NPM_VERSION 2.1.16
   
   RUN curl -SLO "http://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.gz" \
  -  && curl -SLO "http://nodejs.org/dist/v$NODE_VERSION/SHASUMS256.txt.asc" \
  -  && gpg --verify SHASUMS256.txt.asc \
  -  && grep " node-v$NODE_VERSION-linux-x64.tar.gz\$" SHASUMS256.txt.asc | sha256sum -c - \
  -  && tar -xzf "node-v$NODE_VERSION-linux-x64.tar.gz" -C /usr/local --strip-components=1 \
  -  && rm "node-v$NODE_VERSION-linux-x64.tar.gz" SHASUMS256.txt.asc \
  -  && npm install -g npm@"$NPM_VERSION" \
  -  && npm cache clear
  + && curl -SLO "http://nodejs.org/dist/v$NODE_VERSION/SHASUMS256.txt.asc" \
  + && gpg --verify SHASUMS256.txt.asc \
  + && grep " node-v$NODE_VERSION-linux-x64.tar.gz\$" SHASUMS256.txt.asc | sha256sum -c - \
  + && tar -xzf "node-v$NODE_VERSION-linux-x64.tar.gz" -C /usr/local --strip-components=1 \
  + && rm "node-v$NODE_VERSION-linux-x64.tar.gz" SHASUMS256.txt.asc \
  + && npm install -g npm@"$NPM_VERSION" \
  + && npm cache clear
   
   ### Ruby
   RUN apt-get update && apt-get install -y \
       curl \
       procps \
  -  && rm -rf /var/lib/apt/lists/*
  + && rm -rf /var/lib/apt/lists/*
   
   ENV RUBY_MAJOR 2.2
   ENV RUBY_VERSION 2.2.0
  
positive.code:     libxml2-dev \
      libxslt-dev \
      libyaml-dev \
      zlib1g-dev \
    && rm -rf /var/lib/apt/lists/*
  
  ###### Languages
  
  ### Node.js
  RUN apt-get update && apt-get install -y \
      ca-certificates \
    && rm -rf /var/lib/apt/lists/*
  
  # verify gpg and sha256: http://nodejs.org/dist/v0.10.31/SHASUMS256.txt.asc
  # gpg: aka "Timothy J Fontaine (Work) <tj.fontaine@joyent.com>"
  
negative.code: RUN echo 'gem: --no-rdoc --no-ri' >> "$HOME/.gemrc"
  
  ### Java
  RUN echo oracle-java7-installer shared/accepted-oracle-license-v1-1 select true \
    | debconf-set-selections \
   && add-apt-repository -y ppa:webupd8team/java \
   && apt-get update \
   && apt-get install -y \
      oracle-java7-installer \
   && rm -rf /var/lib/apt/lists/* \
   && rm -rf /var/cache/oracle-jdk7-installer
  
  # Define commonly used JAVA_HOME variable
  ENV JAVA_HOME /usr/lib/jvm/java-7-oracle
  
  ### Go
  # SCMs for "go get", gcc for cgo
  RUN apt-get update
   && apt-get install -y \
      ca-certificates \
      curl \
      gcc \
  