anchor.diff:      python2 -m pip install setuptools wheel && \
       python3 -m pip install setuptools wheel && \
       wget -P /usr/local/src/swig \
  -        http://prdownloads.sourceforge.net/swig/swig-4.0.1.tar.gz && \
  -    tar -xf /usr/local/src/swig/swig-4.0.1.tar.gz \
  +        http://prdownloads.sourceforge.net/swig/swig-4.0.2.tar.gz && \
  +    tar -xf /usr/local/src/swig/swig-4.0.2.tar.gz \
           -C /usr/local/src/swig \
           --strip 1 && \
       cd /usr/local/src/swig && \
  
positive.code:         -C /opt/linux/lua54 && \
      cd /usr/local/src && rm -rf ..?* .[!.]* *
  
  # Install macosx build tools (osxcross) and libraries (macports).
  ENV PATH /opt/osxcross/target/bin:${PATH}
  RUN export SDK_VERSION=10.13 &&                               \
      export MACOSX_DEPLOYMENT_TARGET=${SDK_VERSION} &&         \
      export UNATTENDED=1 &&                                    \
      cd /opt &&                                                \
      git clone https://github.com/tpoechtrager/osxcross.git && \
      cd osxcross &&                                            \
      git checkout 1b731164dfd56de2ff20b530ec70c7a88a7b6ea6 &&  \
      wget -P tarballs https://github.com/phracker/MacOSX-SDKs/releases/download/${SDK_VERSION}/MacOSX${SDK_VERSION}.sdk.tar.xz && \
      ./build.sh &&                                             \
      osxcross-macports install                                 \
          lua51                                                 \
          lua52                                                 \
          lua                                                   \
          openjdk8                                              \
          python27                                              \
          python35                                              \
          python36                                              \
          python37                                              \
          python38                                              \
          python39                                              \
          ruby24                                                \
          ruby25                                                \
          ruby26                                                \
          ruby27
  
  # Install windows build tools (mingw) and libraries.
  RUN mkdir -p /opt/wincross/archives                && \
      cd /opt/wincross                               && \
  
negative.code:         make && \
          make install && \
      wget -P /usr/local/src/cmake \
          https://github.com/Kitware/CMake/releases/download/v3.22.1/cmake-3.22.1.tar.gz && \
      tar -xf /usr/local/src/cmake/cmake-3.22.1.tar.gz \
          -C /usr/local/src/cmake \
          --strip 1 && \
      cd /usr/local/src/cmake && \
  