anchor.diff:  
   COPY ./bower.json ./.bowerrc ${KPI_SRC_DIR}/
   # Only install if the current versions of `bower.json` or `.bowerrc` differ from the ones used in the base image.
  -RUN (   diff -q "${KPI_SRC_DIR}/bower.json" /srv/tmp/base_bower.json && \
  -        diff -q "${KPI_SRC_DIR}/.bowerrc" /srv/tmp/base_bowerrc ) || \
  +RUN if [ "$(diff -q ${KPI_SRC_DIR}/bower.json /srv/tmp/base_bower.json && \
  +        diff -q ${KPI_SRC_DIR}/.bowerrc /srv/tmp/base_bowerrc)" ]; then \
       bower install --allow-root --config.interactive=false \
  -    || true # Prevent non-zero exit code.
  +    ; fi
   
   
   ######################
  
positive.code: 
  COPY ./apt_requirements.txt ${KPI_SRC_DIR}/
  # Only install if the current version of `apt_requirements.txt` differs from the one used in the base image.
  RUN diff -q "${KPI_SRC_DIR}/apt_requirements.txt" "/srv/tmp/base_apt_requirements.txt" || \
          ( apt-get update && \
          apt-get install -y $(cat ${KPI_SRC_DIR}/apt_requirements.txt) && \
          apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* ) \ 
      || true # Prevent non-zero exit code.
  
  
  ###########################
  
negative.code: 
  COPY ./package.json ${KPI_SRC_DIR}/
  # Only install if the current version of `package.json` differs from the one used in the base image.
  RUN if [ "$(diff -q ${KPI_SRC_DIR}/package.json /srv/tmp/base_package.json)" ]; then \
      npm install \
      ; fi
  
  
  ##########################################
  