protected function build_sorter( $heading = '' ) {
		$out = '';
		$out .= '<label class="qm-th">';
		$out .= '<span class="qm-sort-heading">';

		if ( '#' === $heading ) {
			$out .= '<span class="qm-screen-reader-text">' . esc_html__( 'Sequence', 'query-monitor' ) . '</span>';
		} elseif ( $heading ) {
			$out .= esc_html( $heading );
		}

		$out .= '</span>';
		$out .= '<button class="qm-sort-controls" aria-label="' . esc_attr__( 'Sort data by this column', 'query-monitor' ) . '">';
		$out .= '<span class="qm-sort-arrow" aria-hidden="true"></span>';
		$out .= '</button>';
		$out .= '</label>';
		return $out;
	}