anchor.diff:  
   RUN apt update && \
       apt -y install \
  -    apt-utils \ 
  +    apt-utils \
  +    software-properties-common \
  +    python-software-properties \
       wget \
       sudo \
       bash \
  
positive.code:     ssh \
      tar \
      gzip \
      build-essential \
      ffmpeg \
      python3-pip \
  
negative.code: FROM ubuntu:16.04
  
  #overrides for APT cache
  RUN echo "force-unsafe-io" > /etc/dpkg/dpkg.cfg.d/02apt-speedup
  RUN echo "Acquire::http {No-Cache=True;};" > /etc/apt/apt.conf.d/no-cache
  
  