code: def write_configuration(self, out, secret_attrs=False):
          
          key_order = ['repo_nexml2json',
                       'number_of_shards',
                       'initialization', ]
          cd = self.get_configuration_dict(secret_attrs=secret_attrs)
          for k in key_order:
              if k in cd:
                  out.write('  {} = {}'.format(k, cd[k]))
          for n, shard in enumerate(self._shards):
              out.write('Shard {}:\n'.format(n))
              shard.write_configuration(out)
docs: Type-specific configuration for backward compatibility