anchor.diff:  
   # Build devevelopment image
   FROM        base as dev
  -LABEL       stage=build
  +LABEL       stage=final
   RUN         apt-get install -y --no-install-recommends --allow-unauthenticated \
               build-essential \
               gcc-7 \
  
positive.code:             #libyaz-dev \
              gcc-7 \
              g++-7 \
           && rm -rf /var/lib/apt/lists/* \
           && apt-get clean \
           && ls -l /usr/bin/g* \
  
negative.code:          && update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-7 20 \
           && update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-8 8 \
           && update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-8 8 \
           #&& update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 9 \
           #&& update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-9 9 \
           && gcc --version \
           && g++ --version
  
  