protected function set_columns() {
		return array(
			'id'          => __( 'ID', 'lifterlms' ),
			'template_id' => __( 'Template ID', 'lifterlms' ),
			'name'        => __( 'Certificate Title', 'lifterlms' ),
			'earned'      => __( 'Earned Date', 'lifterlms' ),
			'related'     => __( 'Related Post', 'lifterlms' ),
			'actions'     => '',
		);
	}