DESCRIPTION¶
Enable or disable heart beat. The driver will apply the lfun heart_beat(A) to the current object every __HEARTBEAT_INTERVAL__ seconds, if it is enabled. A shadow over the heart_beat(A) lfun will be ignored.
If the heart beat is not needed for the moment, then do disable it. This will reduce system overhead.
Return true for success, and false for failure.
Disabling an already disabled heart beat (and vice versa enabling and enabled heart beat) counts as failure.
Note that heart_beat(A) is called only if there are interactive players in the game.