code: def write_burn_in(self, burn_in):
          
          group = self[self.sampler_group]
          group.attrs['burn_in_test'] = burn_in.burn_in_test
          group.attrs['is_burned_in'] = burn_in.is_burned_in
          group.attrs['burn_in_iteration'] = burn_in.burn_in_iteration
          # set the defaut thin_start to be the burn_in_index
          self.thin_start = burn_in.burn_in_index
          # write individual test data
          for tst in burn_in.burn_in_data:
              key = 'burn_in_tests/{}'.format(tst)
              try:
                  attrs = group[key].attrs
              except KeyError:
                  group.create_group(key)
                  attrs = group[key].attrs
              self.write_kwargs_to_attrs(attrs, **burn_in.burn_in_data[tst])
docs: Write the given burn-in data to the given filename.