private static function build_columns($atts)
    {
        /*
         * Get our form object 
         */
        $form = self::$form;
        ?>
			<thead>
				<tr>				
					<?php 
        GFPDFEWidgetsAndShortcode_Shortcode::get_column_name($atts, self::$fields);
        ?>
					<th></th>
				</tr>
			</thead>

		<?php 
    }
    private static function build_columns($atts)
    {
        /*
         * Get our form object 
         */
        $form = self::$form;
        /*
         * start buffering
         */
        ob_start();
        ?>
		<thead>
			<tr>				
		<?php 
        GFPDFEWidgetsAndShortcode_Shortcode::get_column_name($atts, self::$fields);
        if ($atts['pdf']) {
            /*
             * Add blank cell for our PDF header 
             */
            ?>
				<th class="gfpdfePdfHeader"></th>
			<?php 
        }
        /*
         * Add blank cell for our 'edit' header  
         */
        if ($atts['edit'] === true) {
            ?>
				<th class="gfpdfePdfEditHeader"></th>
			<?php 
        }
        ?>

			</tr>
		</thead>

		<?php 
        $html = ob_get_clean();
        return $html;
    }