Test environments

Ubuntu 16.04
- R 3.3.1 (2016-06-21) x86_64-pc-linux-gnu (64-bit)
win-builder (devel and release): http://win-builder.r-project.org/
- R Under development (unstable) (2017-06-12 r71333), platform: x86_64-w64-mingw32 (64-bit)
- R version 3.3.1 (2016-06-21), platform: x86_64-w64-mingw32 (64-bit)

R CMD check results

There were no ERRORs, WARNINGs, or NOTEs.