anchor.diff:     wget \
      sudo \
      libcurl4-openssl-dev \
  -   libxml2-dev 
  +   libxml2-dev \
  +   libgit2-dev
   
   # we need TeX for the rmarkdown package in RStudio, and pandoc is also useful 
   RUN apt-get update 
  
positive.code:    https://archive.linux.duke.edu/cran/src/contrib/brew_1.0-6.tar.gz \
     https://archive.linux.duke.edu/cran/src/contrib/magrittr_1.5.tar.gz \
     https://archive.linux.duke.edu/cran/src/contrib/Archive/roxygen2/roxygen2_5.0.1.tar.gz \
     https://archive.linux.duke.edu/cran/src/contrib/rversions_1.0.3.tar.gz \
     https://archive.linux.duke.edu/cran/src/contrib/git2r_0.25.2.tar.gz \
     
     https://archive.linux.duke.edu/cran/src/contrib/devtools_2.0.1.tar.gz \
     https://archive.linux.duke.edu/cran/src/contrib/R6_2.4.0.tar.gz \
     https://archive.linux.duke.edu/cran/src/contrib/httr_1.4.0.tar.gz \
  
negative.code:     iterators_1.0.10.tar.gz \
      listenv_0.7.0.tar.gz \
      tidyverse_1.2.1.tar.gz \
      promises_1.0.1.tar.
      future_1.9.0.tar.gz \
      doMC_1.3.5.tar.gz \
      foreach_1.4.4.tar.gz \
      doParallel_1.0.11.tar.gz \
  