53:/std/projectile.c (/std/projectile.c)
(public void) enter_env(object to, object from)
/*
 * Function name: enter_env
 * Description  : Update the heap_id when we enter a new environment, so
 *                the projectiles stack correctly.
 *
 * Arguments    : object to - the object we are entering.
 *                object from - the object we come from.
 */
