docs: def get_time(self, idx=0):
          """Return the time of the tif data since the epoch
  
          The time is stored in the "61238" tag.
          """
          timestr = SingleTifPhasics._get_meta_data(path=self.path,
                                                    section="acquisition info",
                                                    name="date & heure")
          if timestr is not None:
              timestr = timestr.split(".")
              # '2016-04-29_17h31m35s.00827'
              structtime = time.strptime(timestr[0],
                                         "%Y-%m-%d_%Hh%Mm%Ss")
              fracsec = float(timestr[1]) * 1e-5
              # use calendar, because we need UTC
              thetime = calendar.timegm(structtime) + fracsec
          else:
              thetime = np.nan
          return thetime