old_contents: from hdfs import InsecureClient, Client
  from collections.abc import Callable
  
  import os
  
  
  def maybe_get_hdfs_client(hdfs_url: str, hdfs_user: str) -> Client:
      if hdfs_url is None:
          return None
      else:
          assert hdfs_user is not None
          return InsecureClient(hdfs_url, user=hdfs_user)
  
  
  def is_hdfs_directory(hdfs_client: Client, path: str):
      return hdfs_client.status(path)["type"] == "DIRECTORY"
  
  
  def walk_hdfs_directory(hdfs_client: Client, path: str, accept_filename_fun: Callable[[str], bool]):
      return (os.path.join(dpath, fname) for dpath, _, fnames in hdfs_client.walk(path) for fname in fnames if accept_filename_fun(fname))
  
new_contents: from hdfs import InsecureClient, Client
  from typing import Callable
  
  import os
  
  
  def maybe_get_hdfs_client(hdfs_url: str, hdfs_user: str) -> Client:
      if hdfs_url is None:
          return None
      else:
          assert hdfs_user is not None
          return InsecureClient(hdfs_url, user=hdfs_user)
  
  
  def is_hdfs_directory(hdfs_client: Client, path: str):
      return hdfs_client.status(path)["type"] == "DIRECTORY"
  
  
  def walk_hdfs_directory(hdfs_client: Client, path: str, accept_filename_fun: Callable[[str], bool]):
      return (os.path.join(dpath, fname) for dpath, _, fnames in hdfs_client.walk(path) for fname in fnames if accept_filename_fun(fname))
  
subject: fix type hint