System requirements: An available hiredis library (eg via package
libhiredis-dev on Debian/Ubuntu, hiredis-devel on
Fedora/RedHat, or directly from source from
<https://github.com/redis/hiredis>) can be used but version
1.0.2 is also included and built on demand if needed. The
optional (but suggested) 'rredis' package can be installed from
the 'ghrr' 'drat' repo for additional illustrations and tests.