options(repos=structure(c(CRAN="http://cran.wustl.edu/")))
if (!requireNamespace("devtools")) {
  install.packages("devtools")
}
if (!requireNamespace("roxygen2")) {
  install.packages("roxygen2")
}
if (!requireNamespace("knitr")) {
  install.packages("knitr")
}
if (!requireNamespace("markdown")) {
  install.packages("markdown")
}

devtools::install_dev_deps()