NAME
	heart_beat - a regularly called function

SYNTAX
	void heart_beat() { ... }

DESCRIPTION
	If an object calls set_heart_beat(1) then this function will be
	called in that object regularly. (normally the delay is 2 seconds)
	To stop the calling of heart_beat(), call set_heart_beat(0).

SEE ALSO
	efun/set_heart_beat
