docstr: Iterable batch holding a list of ray.ObjectRefs.
  
  Args:
      shard_id (int): id of the shard
      prefix (str): prefix name of the batch
      obj_refs (List[ray.ObjectRefs]): list of ray.ObjectRefs
code: def __init__(self, shard_id: int, obj_refs: "ray.ObjectRef"):
      """Iterable batch holding a list of ray.ObjectRefs.
  
      Args:
          shard_id (int): id of the shard
          prefix (str): prefix name of the batch
          obj_refs (List[ray.ObjectRefs]): list of ray.ObjectRefs
      """
      self._shard_id = shard_id
      self._obj_refs = obj_refs
  
file_path: mars/mars/dataframe/contrib/raydataset/mldataset.py
imports: import numpy
  import pandas
  from collections import defaultdict
  from typing import Dict, Iterable, List, Tuple
  from ....utils import lazy_import
label_desc: Use image node_id 1 to create a new ChunkRefBatch object  with example: obj = ChunkRefBatch(shard_id, obj_refs)