code: def _validate_data(self, folder: str) -> None:
      msg = f"The provided dataset for stage {self._running_stage} should be a folder. Found {folder}."
      if not isinstance(folder, str):
          raise ValueError(msg)
  
      if isinstance(folder, str) and not isdir(folder):
          raise ValueError(msg)
  
imports: import os
  from os.path import basename, dirname, exists, isdir, isfile, join
  from typing import Any, Dict, List, Optional, Type, Union
  import yaml
  from flash.core.data.io.input import BaseDataFormat, Input
  from flash.core.utilities.imports import _TOPIC_POINTCLOUD_AVAILABLE
label_desc: Use image node_id 2 for calling the PointCloudObjectDetectorFoldersInput obj's underlying member method code with example usage: obj._validate_data(folder) without return types