getRefreshIntervals example

'#description' => $this->t("How many time units will be used in formatting the time difference. For example, if '1' is selected then the displayed time difference will only contain a single time unit such as '2 years' or '5 minutes' never '2 years 3 months' or '5 minutes 8 seconds'."),
      '#default_value' => $time_diff['granularity'],
      '#options' => array_combine(range(1, 7), range(1, 7)),
      '#states' => $states,
    ];

    $form['time_diff']['refresh'] = [
      '#type' => 'select',
      '#title' => $this->t('Refresh interval'),
      '#description' => $this->t('How often to refresh the displayed time difference. The time difference is refreshed on client-side, by JavaScript, without reloading the page.'),
      '#default_value' => $time_diff['refresh'],
      '#options' => $this->getRefreshIntervals(),
      '#states' => $states,
    ];

    $form['time_diff']['description'] = [
      '#type' => 'item',
      '#title' => $this->t('Fallback configuration'),
      '#description' => $this->t('The configuration below is used as a fallback when JavaScript is not available on the page.'),
      '#states' => $states,
    ];

    $form['date_format'] = [