code: def remove_cycle_mrkr(self, epoch_start):
          
          if self.rater is None:
              raise IndexError('You need to have at least one rater')
          cycles = self.rater.find('cycles')
          for one_mrkr in cycles.iterfind('cyc_start'):
              if int(one_mrkr.text) == epoch_start:
                  cycles.remove(one_mrkr)
                  self.save()
                  return
  
          for one_mrkr in cycles.iterfind('cyc_end'):
              if int(one_mrkr.text) == epoch_start:
                  cycles.remove(one_mrkr)
                  self.save()
                  return
  
          raise KeyError('cycle marker at ' + str(epoch_start) + ' not found')
docs: Remove cycle marker at epoch_start.
  
          Parameters
          ----------
          epoch_start: int
              start time of epoch, in seconds