public function toggleClasses( array $classes, $toggle = null ) {
		if ( $toggle === null ) {
			$this->classes = array_diff(
				array_merge( $this->classes, $classes ),
				array_intersect( $this->classes, $classes )
			);
		} elseif ( $toggle ) {
			$this->classes = array_merge( $this->classes, $classes );
		} else {
			$this->classes = array_diff( $this->classes, $classes );
		}
		return $this;
	}