public function createFieldset($legend = null, $container = null)
    {
        $fieldset = new Fieldset();
        if (null !== $legend) {
            $fieldset->setLegend($legend);
        }
        if (null !== $container) {
            $fieldset->setContainer($container);
        }
        $this->addFieldset($fieldset);
        $id = (null !== $this->getAttribute('id')) ?
            $this->getAttribute('id') . '-fieldset-' . ($this->current + 1) : 'pop-form-fieldset-' . ($this->current + 1);
        $class = (null !== $this->getAttribute('class')) ?
            $this->getAttribute('id') . '-fieldset' : 'pop-form-fieldset';
        $fieldset->setAttribute('id', $id);
        $fieldset->setAttribute('class', $class);
        return $fieldset;
    }