anchor.diff:      -DBUILD_EXAMPLES:BOOL=OFF \
       -DBUILD_SHARED_LIBS:BOOL=ON \
       -DCMAKE_INSTALL_PREFIX:PATH=/opt/itk \
  +    -DPYTHON_EXECUTABLE:PATH=/usr/bin/python3 \
       ../ITK && \
     cmake --build . --target install && \
     cd .. && \
  
positive.code:     -DVTK_PYTHON_FULL_THREADSAFE:BOOL=ON \
      -DVTK_NO_PYTHON_THREADS:BOOL=OFF \
      -DQt5_DIR:PATH=/usr/local/Qt-5.8.0/lib/cmake/Qt5 \
      ../paraview && \
    cmake --build . && \
    cd .. && \
  
negative.code:   wget \
    cmake \
    python \
    python3 \
    python3-pip \
    python3-dev \
    g++ \
    libtbb-dev \
    libgl1-mesa-dev \
    libglu1-mesa-dev \
    libxt-dev
  
  RUN pip3 install -U pip && \
    pip3 install numpy
  
  # Build and install ninja.
  ARG NINJA_VERSION=v1.7.2
  