docs: def write_rec(table_name, objid, data, index_name_values):
      """Write (upsert) a record using a tran."""
      with DatastoreTransaction() as tx:
          entity = tx.get_upsert()
  
          entity.key.CopyFrom(make_key(table_name, objid))
  
          prop = entity.property.add()
          prop.name = 'id'
          prop.value.string_value = objid
  
          prop = entity.property.add()
          prop.name = 'value'
          prop.value.string_value = data
  
          for name, val in index_name_values:
              prop = entity.property.add()
              prop.name = name
              prop.value.string_value = str(val)