anchor.diff:  
   # llvm needs CMake 2.8.12.2 or higher
   # https://cmake.org/download/
  -RUN wget https://cmake.org/files/v3.6/cmake-3.6.1.tar.gz \
  -	&& tar xf cmake-3.6.1.tar.gz && cd cmake-3.6.1 \
  +ENV CMAKE_VER_MAJ 3.6
  +ENV CMAKE_VER_MIN .1
  +ENV CMAKE_VER $CMAKE_VER_MAJ$CMAKE_VER_MIN
  +
  +RUN wget https://cmake.org/files/v$CMAKE_VER_MAJ/cmake-$CMAKE_VER.tar.gz \
  +	&& tar xf cmake-$CMAKE_VER.tar.gz && cd cmake-$CMAKE_VER \
   	&& ./bootstrap && make -j"$(nproc --all)" && make -j"$(nproc --all)" install \
  -	&& cd .. && rm -rf cmake-3.6.1 && rm -f cmake-3.6.1.tar.gz \
  -	&& echo "export CMAKE_ROOT=/usr/local/share/cmake-3.6" > /etc/profile.d/cmake-root.sh \
  +	&& cd .. && rm -rf cmake-$CMAKE_VER && rm -f cmake-$CMAKE_VER.tar.gz \
  +	&& echo "export CMAKE_ROOT=/usr/local/share/cmake-$CMAKE_VER_MAJ" > /etc/profile.d/cmake-root.sh \
   	&& source /etc/profile
   
  -# Python 2.7
  +# Python 2
   # https://github.com/h2oai/h2o-2/wiki/Installing-python-2.7-on-centos-6.3.-Follow-this-sequence-exactly-for-centos-machine-only
  -RUN wget https://www.python.org/ftp/python/2.7.11/Python-2.7.11.tar.xz \
  -	&& tar xf Python-2.7.11.tar.xz \
  -	&& cd Python-2.7.11 \
  -	&& ./configure --prefix=/usr/local/python2.7 --enable-shared --with-cxx-main=/usr/bin/g++ \
  +ENV PYTHON2_VER_MAJ 2.7
  +ENV PYTHON2_VER_MIN .11
  +ENV PYTHON2_VER $PYTHON2_VER_MAJ$PYTHON2_VER_MIN
  +
  +RUN wget https://www.python.org/ftp/python/$PYTHON2_VER/Python-$PYTHON2_VER.tar.xz \
  +	&& tar xf Python-$PYTHON2_VER.tar.xz \
  +	&& cd Python-$PYTHON2_VER \
  +	&& ./configure --prefix=/usr/local/python$PYTHON2_VER_MAJ --enable-shared --with-cxx-main=/usr/bin/g++ \
   	&& make -j"$(nproc --all)" \
   	&& make -j"$(nproc --all)" altinstall \
   	&& echo "/usr/local/lib" > /etc/ld.so.conf.d/usrLocalLib.conf \
   	&& ldconfig \
  -	&& cd .. && rm -f Python-2.7.11.tar.xz && rm -rf Python-2.7.11
  +	&& cd .. && rm -f Python-$PYTHON2_VER.tar.xz && rm -rf Python-$PYTHON2_VER
   
   # pip for Python 2
   RUN curl -O https://bootstrap.pypa.io/get-pip.py \
  -	&& /usr/local/python2.7/bin/python2.7 get-pip.py \
  +	&& /usr/local/python$PYTHON2_VER_MAJ/bin/python$PYTHON2_VER_MAJ get-pip.py \
   	&& rm -f get-pip.py
   
   # Python 3
  -RUN wget https://www.python.org/ftp/python/3.5.1/Python-3.5.1.tar.xz \
  -	&& tar xf Python-3.5.1.tar.xz && cd Python-3.5.1 \
  +ENV PYTHON3_VER_MAJ 3.5
  +ENV PYTHON3_VER_MIN .1
  +ENV PYTHON3_VER $PYTHON3_VER_MAJ$PYTHON3_VER_MIN
  +
  +RUN wget https://www.python.org/ftp/python/$PYTHON3_VER/Python-$PYTHON3_VER.tar.xz \
  +	&& tar xf Python-$PYTHON3_VER.tar.xz && cd Python-$PYTHON3_VER \
   	&& ./configure --prefix=/usr/local --enable-shared --with-cxx-main=/usr/bin/g++ \
   	&& echo "zlib zlibmodule.c -I\$(prefix)/include -L\$(exec_prefix)/lib -lz" >> ./Modules/Setup \
   	&& make -j"$(nproc --all)" \
   	&& make -j"$(nproc --all)" altinstall \
  -	&& ln -s /usr/local/bin/python3.5 /usr/local/bin/python3 \
  -	&& ln -s /usr/local/bin/pip3.5 /usr/local/bin/pip3 \
  +	&& ln -s /usr/local/bin/python$PYTHON3_VER_MAJ /usr/local/bin/python3 \
  +	&& ln -s /usr/local/bin/pip$PYTHON3_VER_MAJ /usr/local/bin/pip3 \
   	&& ldconfig \
  -	&& cd .. && rm -f Python-3.5.1.tar.xz && rm -rf Python-3.5.1
  +	&& cd .. && rm -f Python-$PYTHON3_VER.tar.xz && rm -rf Python-$PYTHON3_VER
   
   # Upgrade pip
   # https://pip.pypa.io/en/stable/installing/#upgrading-pip
  
positive.code: RUN julia -e 'Pkg.add("IJulia"); using IJulia'
  
  # registers global kernel
  RUN cp -r ~/.local/share/jupyter/kernels/julia-0.4 /usr/local/share/jupyter/kernels
  
  # rewrite julia's kernel configuration
  ADD julia-kernel.json /usr/local/share/jupyter/kernels/julia-0.4/kernel.json
  
  # R
  # http://irkernel.github.io/installation/
  
negative.code: RUN pip3 install -U pip
  
  # LLVM deps
  # TODO: check if python-devel is needed
  RUN yum -y install \
  	libedit-devel \
  	libffi-devel \
  	swig \
  	python-devel \
  	&& yum clean all
  
  # LLVM
  # Clang /tools/clang
  