re will be _nothing_ that would yield a true formula when put into PRED's functional argument-place; for example, while a spatial thing has at most one length (see #$lengthOfObject), if it is (say) a sphere it has none. A binary #$FunctionalPredicate that is functional in its second argument is an instance of #$FunctionalSlot (q.v.).<br />
	    guid: bd58dc77-9c29-11b1-9dad-c379636f7270<br />
	    direct instance of: #$PredicateCategory #$AtemporalNecessarilyEssentialCollectionType<br />
	    direc