GC
(GC anything)

	command.  Runs the garbage collector, reclaiming unused nodes.  Logo
	does this when necessary anyway, but you may want to use this
	command to control exactly when Logo does it.  In particular, the
	numbers output by the NODES operation will not be very meaningful
	unless garbage has been collected.  Another reason to use GC is that
	a garbage collection takes a noticeable fraction of a second, and you
	may want to schedule collections for times before or after some
	time-critical animation.  If invoked with an input (of any value),
	GC runs a full garbage collection, including GCTWA (Garbage Collect
	Truly Worthless Atoms, which means that it removes from Logo's
	memory words that used to be procedure or variable names but aren't
	any more); without an input, GC does a generational garbage
	collection, which means that only recently created nodes are
	examined.  (The latter is usually good enough.)

