code: def test_loc(dir_server):
      root = "http://localhost:8999/"
      fn = files[0]
      f = open_files(root + fn)[0]
      with open(os.path.join(dir_server, fn), "rb") as expected:
          expected = expected.read()
          with f as f:
              data = f.read(2)
              assert data == expected[:2]
              assert f.loc == 2
              f.seek(0)
              data = f.read(3)
              assert data == expected[:3]
              f.seek(1, 1)
              assert f.loc == 4
  
imports: from __future__ import annotations
  import os
  import subprocess
  import sys
  import time
  import fsspec
  import pytest
  from fsspec.core import open_files
  from packaging.version import parse
  import dask.bag
  from dask.utils import tmpdir
label_desc: Use image node_id 3 for calling a global function with example usage: test_loc(dir_server) without return types