code: def all_valid_time_intervals():
          '''
          Helper method to return all possible valid time intervals for data
          stored by Perfherder
          '''
          return [PerformanceTimeInterval.DAY,
                  PerformanceTimeInterval.WEEK,
                  PerformanceTimeInterval.TWO_WEEKS,
                  PerformanceTimeInterval.SIXTY_DAYS,
                  PerformanceTimeInterval.NINETY_DAYS,
                  PerformanceTimeInterval.ONE_YEARf all_valid_time_intervals():
          '''
          Helper method to return all possible valid time intervals for data
          stored by Perfherder
          '''
          return [PerformanceTimeInterval.DAY,
                  PerformanceTimeInterval.WEEK,
                  PerformanceTimeInterval.TWO_WEEKS,
                  PerformanceTimeInterval.SIXTY_DAYS,
                  PerformanceTimeInterval.NINETY_DAYS,
                  PerformanceTimeInterval.ONE_YEAR]
docs: Helper method to return all possible valid time intervals for data
          stored by Perfherder