private function get_count_suffix( string $event, bool $increment = false ): string {

		if ( ! isset( $this->calls[ $event ] ) ) {
			$this->calls[ $event ] = 0;
		}

		if ( $increment ) {
			$this->calls[ $event ] ++;
		}

		$count = (int) $this->calls[ $event ];

		return $count > 1 ? " ({$count})" : '';
	}