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:     iterators_1.0.10.tar.gz \
      listenv_0.7.0.tar.gz \
      tidyverse_1.2.1.tar.gz \
      promises_1.0.1.tar.fs_1.2.7.tar.gz    future_1.9.0.tar.gz \
      doMC_1.3.5.tar.gz \
      foreach_1.4.4.tar.gz \
      doParallel_1.0.11.tar.gz \
  
negative.code: 
  RUN DEBIAN_FRONTEND=noninteractive R CMD INSTALL \
      modelr_0.1.2.tar.gz \
      prex_0.2.0.tar.gz \
      tidyverse_1.2.1.tar.gz \
      promises_1.0.1.tar.gz \
      globals_0.12.2.tar.gz \
  