class_docstr: Flattened access to a collection of datasets.
class_docstr_tok: ["Flattened","access","to","a","collection","of","datasets","."]
code: def __len__(self):
      return sum(map(len, self.datasets))
  
file_path: gluonts/src/gluonts/dataset/__init__.py
imports: from dataclasses import dataclass
  from pathlib import Path
  from typing import Any, Dict, Iterator, List, Optional
  from typing_extensions import Protocol, runtime_checkable
  from gluonts.itertools import roundrobin
label_desc: Use image node_id 4 for calling the DatasetCollection obj's underlying member method code with example usage: obj.__len__() and returns: sum