timer-inc-time
timer-inc-time is a compiled Lisp function in `timer.el
'.
(timer-inc-time TIMER SECS &optional USECS PSECS)
Increment the time set in TIMER by SECS seconds, USECS microseconds,
and PSECS picoseconds. SECS may be a fraction. If USECS or PSECS are
omitted, they are treated as zero.