Test environments OS X 10.12.6 (on travis-ci), R 3.5.0 Ubuntu 14.04 (on travis-ci), R 3.5.0 Windows i386-w64-mingw32 (on appveyor), R 3.5.0 Patched (2018-05-21 r74756) Ubuntu 17.10, R 3.4.2 R CMD check results None Downstream dependencies There are no downstream dependencies at this point.