isatty - Determine if a stream is connected to a terminal.
stream isatty -> false|true
Alternatives: Functions isatty_is for istreams, isatty_os
for osstreams (both undocumented) -> behaviour and synopsis are the same.
This is a wrapper to the POSIX kernel function istty().
/var/www/debian/nest/nest-simulator-2.20.0/lib/sli/processes.sli