code: def open(self, mode):
          
          if self.hdf5 == ():  # not already open
              kw = dict(mode=mode, libver='latest')
              if mode == 'r':
                  kw['swmr'] = True
              try:
                  self.hdf5 = hdf5.File(self.filename, **kw)
              except OSError as exc:
                  raise OSError('%s in %s' % (exc, self.filename))
docs: Open the underlying .hdf5 file and the parent, if any