code: def GetFrequencyStartTimes(self):
      
      start_times = []
      # for each headway period of the trip
      for freq_tuple in self.GetFrequencyTuples():
        (start_secs, end_secs, headway_secs) = freq_tuple[0:3]
        # reset run secs to the start of the timeframe
        run_secs = start_secs
        while run_secs < end_secs:
          start_times.append(run_secs)
          # increment current run secs by headway secs
          run_secs += headway_secs
      return start_times
docs: Return a list of start time for each headway-based run.
  
      Returns:
        a sorted list of seconds since midnight, the start time of each run. If
        this trip doesn't have headways returns an empty list.