## Test environments
* local Arch Linux install, R version 4.0.3
* r-hub (Debian, clang/gcc, R-devel)
* r-hub (Fedora, clang+gfortran, R-devel)
* r-hub (macOS 10.13.6 High Sierra, R release)
* r-hub (Solaris 10, 32-bit, R release)
* r-hub (Windows server 2008, R-devel)
* win-builder (R-devel)

## R CMD check results
There were no ERRORs or WARNINGs or NOTEs.