code: function groupDate({creationDate: date}) {
      const root = 'focus.notifications.groups';
      if(_isYoungerThanA('day', date)) {
          return `${root}.0_today`;
      }
      if(_isYoungerThanA('week', date)) {
          return `${root}.1_lastWeek`;
      }
      if(_isYoungerThanA('month', date)) {
          return `${root}.2_lastMonth`;
      }
      return `${root}.3_before`;
  }
docs: function to group date