code: def GetFrequencyStartTimes(self):
      start_times = []
      for freq_tuple in self.GetFrequencyTuples():
        (start_secs, end_secs, headway_secs) = freq_tuple[0:3]
        run_secs = start_secs
        while run_secs < end_secs:
          start_times.append(run_secs)
          run_secs += headway_secs
      return start_times