public function render() {
		// execute callback if we have one first
		if ( is_closure( $this->value ) ) {
			ob_start(); $return = call_user_func( $this->value ); $this->value = ob_get_clean().$return;
		}
		return '<'.$this->name.static::attr( $this->attr ).
			( !is_null( $this->value ) ? '>'.$this->value.'</'.$this->name.'>' : ' />' );
	}