anchor.diff:     curl_3.2.tar.gz \
      openssl_1.0.2.tar.gz \
      httr_1.3.1.tar.gz \
  -   rstudioapi_0.7.tar.gz \
  +   rstudioapi_0.10.tar.gz \
      withr_2.1.2.tar.gz \
      git2r_0.23.0.tar.gz \
      devtools_1.13.6.tar.gz \
  
positive.code: 
  # R packages we need for devtools - and we need devtools to be able to update the rmarkdown package
  RUN DEBIAN_FRONTEND=noninteractive wget \
     https://mirrors.nics.utk.edu/cran/src/contrib/rstudioapi_0.7.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/openssl_1.0.2.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/withr_2.1.2.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/brew_1.0-6.tar.gz \
  
negative.code:    plyr_1.8.4.tar.gz \
     R6_2.2.2.tar.gz \
     httr_1.3.1.tar.gz \
     rstudioapi_0.10.tar.gz \
     openssl_1.0.2.tar.gz \
     withr_2.1.2.tar.gz \
     brew_1.0-6.tar.gz \
  