code: def _init_storage(storage_uri: str, is_head: bool):
      """Init global storage.
  
      On the head (ray start) process, this also creates a _valid file under the given
      storage path to validate the storage is writable. This file is also checked on each
      worker process to validate the storage is readable. This catches common errors
      like using a non-NFS filesystem path on a multi-node cluster.
  
      On worker nodes, the actual filesystem is lazily initialized on first use.
      """
      global _storage_uri
  
      if storage_uri:
          _storage_uri = storage_uri
          if is_head:
              _init_filesystem(create_valid_file=True)
  
imports: import os
  import re
  import urllib
  from pathlib import Path
  from typing import TYPE_CHECKING, List, Optional
  from ray._private.client_mode_hook import client_mode_hook
  from ray._private.utils import _add_creatable_buckets_param_if_s3_uri, load_class
  from ray._private.auto_init_hook import wrap_auto_init
label_desc: Use image node_id 4 for calling a global function with example usage: _init_storage(storage_uri, is_head) without return types