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.