anchor.diff:  #     Use 'docker run' without '--rm' flag for keeping the container and use
   #     'docker commit <container hash> <new image>' to extend the original image
   
  -FROM ubuntu:18.04
  +FROM ubuntu:20.04
   
   # configure locale
  -RUN apt update -qq > /dev/null && apt install -qq --yes --no-install-recommends \
  +RUN apt -y update -qq > /dev/null \
  +    && DEBIAN_FRONTEND=noninteractive apt install -qq --yes --no-install-recommends \
       locales && \
       locale-gen en_US.UTF-8
   ENV LANG="en_US.UTF-8" \
       LANGUAGE="en_US.UTF-8" \
       LC_ALL="en_US.UTF-8"
   
  -RUN apt -y update -qq > /dev/null && apt -y install -qq --no-install-recommends \
  +RUN apt -y update -qq > /dev/null \
  +    && DEBIAN_FRONTEND=noninteractive apt install -qq --yes --no-install-recommends \
   	ca-certificates \
       curl \
       && apt -y autoremove \
  
positive.code: # install system dependencies
  RUN dpkg --add-architecture i386 \
      && ${RETRY} apt -y update -qq > /dev/null \
      && ${RETRY} apt -y install -qq --no-install-recommends \
      autoconf \
      automake \
      autopoint \
  
negative.code:     libidn11:i386 \
      libltdl-dev \
      libncurses5:i386 \
      libssl-dev \
      libstdc++6:i386 \
      libtool \
  