co-maintainers welcome lssndrbarbieri@gmail.com Alessandro Barbieri An extension to stopifnot() that makes it easy to declare the pre and post conditions that you code should satisfy, while also producing friendly error messages so that your users know what's gone wrong. https://cran.r-project.org/web/packages/assertthat/assertthat.pdf Hadley Wickham hadley@rstudio.com