anchor.diff:     http://archive.linux.duke.edu/cran/src/contrib/xml2_1.0.0.tar.gz \
      http://archive.linux.duke.edu/cran/src/contrib/curl_2.3.tar.gz \
      http://archive.linux.duke.edu/cran/src/contrib/jsonlite_1.1.tar.gz \
  -   http://archive.linux.duke.edu/cran/src/contrib/digest_0.6.10.tar.gz \
  +   http://archive.linux.duke.edu/cran/src/contrib/digest_0.6.12.tar.gz \
      http://archive.linux.duke.edu/cran/src/contrib/downloader_0.4.tar.gz \
      http://archive.linux.duke.edu/cran/src/contrib/memoise_1.0.0.tar.gz \
      http://archive.linux.duke.edu/cran/src/contrib/plyr_1.8.4.tar.gz \
  
positive.code: 
  RUN DEBIAN_FRONTEND=noninteractive R CMD INSTALL \
     jsonlite_1.1.tar.gz \
     digest_0.6.10.tar.gz \
     memoise_1.0.0.tar.gz \
     whisker_0.3-2.tar.gz \
     bitops_1.0-6.tar.gz \
  
negative.code: 
  RUN rm \
     jsonlite_1.1.tar.gz \
     digest_0.6.12.tar.gz \
     memoise_1.0.0.tar.gz \
     whisker_0.3-2.tar.gz \
     bitops_1.0-6.tar.gz \
  