anchor.diff:     https://mirrors.nics.utk.edu/cran/src/contrib/R6_2.2.2.tar.gz \
      https://mirrors.nics.utk.edu/cran/src/contrib/magrittr_1.5.tar.gz \
      https://mirrors.nics.utk.edu/cran/src/contrib/lazyeval_0.2.1.tar.gz \
  -   https://mirrors.nics.utk.edu/cran/src/contrib/DBI_0.7.tar.gz 
  +   https://mirrors.nics.utk.edu/cran/src/contrib/DBI_0.8.tar.gz 
   
   
   
  
positive.code:    R6_2.2.2.tar.gz \
     magrittr_1.5.tar.gz \
     lazyeval_0.2.1.tar.gz \
     DBI_0.7.tar.gz \
     tibble_1.4.2.tar.gz \
     glue_1.2.0.tar.gz \
     pkgconfig_2.0.1.tar.gz \
     plogr_0.1-1.tar.gz \
     bindr_0.1.tar.gz \
     bindrcpp_0.2.tar.gz \
     dplyr_0.7.4.tar.gz 
  
  
negative.code: RUN DEBIAN_FRONTEND=noninteractive wget \
     https://mirrors.nics.utk.edu/cran/src/contrib/openintro_1.7.1.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/tibble_1.4.2.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/bindr_0.1.1.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/bindrcpp_0.2.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/glue_1.2.0.tar.gz \
     https://mirrors.nics.utk.edu/cran/src/contrib/pkgconfig_2.0.1.tar.gz \
  