class_docstr: Adds an id to the time series. For rolling test sets
  the time series that are an extension of each other have the same id.
code: def __init__(self, required_length: int = 0):
      self.required_length = required_length
  
file_path: gluonts/src/gluonts/nursery/few_shot_prediction/src/meta/datasets/preprocessing/transform.py
imports: from abc import ABC, abstractmethod
  import json
  from itertools import cycle
  from pathlib import Path
  from typing import List, Optional, Any, Dict
  from gluonts.dataset.field_names import FieldName
  from .filters import Filter
label_desc: Use image node_id 1 to create a new ItemIDTransform object from inherited base classes: Transform with example: obj = ItemIDTransform(required_length)