FILE
	/usr/common/sys/timed.c

NAME
	set_heart_beat - schedule a function to be called at set intervals

PROTOTYPE
	void set_heart_beat(int how_often, string funcname, mixed args...)

CALLED BY
	System, Common, Game

DESCRIPTION
	The set_heart_beat() function works just like call_out()
	except for an extra parameter on the front, which determines
	how often it should be called.  How_often is an enumerated
	constant in timed.h, and has values like TIMED_HALF_MINUTE
	for a timer called once per 30 seconds.  See
	phantasmal/timed.h for legal values.

	Each object may have no more than one heart_beat function
	of any given frequency.  For instance, it may have one
	each of TIMED_TEN_MINUTES and TIMED_ONE_HOUR, but may not
	have two heart_beat functions that each run once per
	TIMED_ONE_HOUR.

	An object may only set_heart_beat for itself, which means
	that the object calling TIMED->set_heart_beat must name
	one of its own functions.  The function named must be
	callable by TIMED, so static and private functions don't
	work.  It's a good idea to make sure that TIMED actually
	is the object calling the heart_beat function, though.

RETURN VALUE
	None.

ERRORS
	Bad parameters or problems setting up a call_out can cause errors.
	An error can also occur if that object has already set a heart_beat
	of that frequency.

SEE ALSO
	stop_heart_beat