function(){
		return underscore.reduce(arguments, function(first, second){
			return underscore.union(
				underscore.difference(first, second),
				underscore.difference(second, first)
			);
		});
	}
function(){
		return underscore.reduce(arguments, function(first, second){
			return underscore.union(
				underscore.difference(first, second),
				underscore.difference(second, first)
			);
		});
	}
function ( ) { return underscore . reduce ( arguments , function ( first , second ) { return underscore . union ( underscore . difference ( first , second ) , underscore . difference ( second , first ) ) ; } ) ; }
### symmetricDifference*(set1, set2[, ...setN])* The symmetric of two sets is is the set of elements in either set, but not their intersection. If two sets are equal, the symmetric difference is empty.
### symmetricDifference * ( set1 set2 [ ... setN ] ) * The symmetric of two sets is is the set of elements in either set but not their intersection . If two sets are equal the symmetric difference is empty .