anchor.diff:     stringr_1.2.0.tar.gz \
      roxygen2_5.0.1.tar.gz \
      BH_1.62.0-1.tar.gz \
  -   XML_3.98-1.7.tar.gz \
  +   XML_3.98-1.9.tar.gz \
      xml2_1.1.1.tar.gz \
      curl_2.6.tar.gz \
      rversions_1.0.3.tar.gz \
      git2r_0.18.0.tar.gz \
  -   devtools_1.13.1.tar.gz \
  +   devtools_1.13.2.tar.gz \
      downloader_0.4.tar.gz
   
      
  
positive.code:    http://archive.linux.duke.edu/cran/src/contrib/Archive/roxygen2/roxygen2_5.0.1.tar.gz \
     http://archive.linux.duke.edu/cran/src/contrib/rversions_1.0.3.tar.gz \
     http://archive.linux.duke.edu/cran/src/contrib/git2r_0.18.0.tar.gz \
     http://archive.linux.duke.edu/cran/src/contrib/devtools_1.13.1.tar.gz \
     http://archive.linux.duke.edu/cran/src/contrib/R6_2.2.1.tar.gz \
     http://archive.linux.duke.edu/cran/src/contrib/mime_0.5.tar.gz \
     http://archive.linux.duke.edu/cran/src/contrib/httr_1.2.1.tar.gz \
     http://archive.linux.duke.edu/cran/src/contrib/RCurl_1.95-4.8.tar.gz \
  
negative.code: RUN rm \
     openintro_1.4.tar.gz \
     assertthat_0.2.0.tar.gz \
     R6_2.2.2.tar.gz \
     magrittr_1.5.tar.gz \
     lazyeval_0.2.0.tar.gz \
     DBI_0.6-1.tar.gz \
  