code: def sample_n_frac(request):
      """
      Specific to `test_sample*` tests.
      """
      n, frac = request.param
      if n is not None and frac is not None:
          pytest.skip("Cannot specify both n and frac.")
      return n, frac
  
imports: import itertools
  import os
  import pathlib
  import cupy
  import numpy
  import pytest
  import rmm
  import cudf
  from cudf.testing._utils import assert_eq
label_desc: Use image node_id 2 for calling a global function with example usage: sample_n_frac(request) and returns: n,  frac