function nary() {
		var args;
		var i;

		args = [];
		for ( i = 0; i < arguments.length; i++ ) {
			args.push( arguments[ idx[i] ] );
		}
		return fcn.apply( thisArg, args );
	}
Invokes a function according to an argument mask.

@private
@param {...*} args - arguments
@returns {*} return value