anchor.diff:  
   # R packages we need for devtools - and we need devtools to be able to update the rmarkdown package
   RUN DEBIAN_FRONTEND=noninteractive wget \
  +   https://archive.linux.duke.edu/cran/src/contrib/processx_3.3.0.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/callr_3.2.0.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/cli_1.1.0.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/pkgbuild_1.0.2.tar.gz \
  
positive.code:     https://archive.linux.duke.edu/cran/src/contrib/microbenchmark_1.4-4.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/modelr_0.1.2.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/clipr_0.4.1.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/processx_3.2.0.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/ps_1.1.0.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/globals_0.12.2.tar.gz \
      https://archive.linux.duke.edu/cran/src/contrib/listenv_0.7.0.tar.gz \
  
negative.code:     globals_0.12.2.tar.gz \
      iterators_1.0.10.tar.gz \
      listenv_0.7.0.tar.gz \
      clipr_0.4.1.tar.gz \
      tidyverse_1.2.1.tar.gz \
      promises_1.0.1.tar.gz \
  