code: def test_unknown_chunk_sizes(internal_method):
      x = da.random.default_rng().random(1000, chunks=(100,))
      x._chunks = ((np.nan,) * 10,)
  
      result = da.percentile(
          x, 50, internal_method=internal_method
      ).compute()
      assert 0.1 < result < 0.9
  
      a, b = da.percentile(
          x, [40, 60], internal_method=internal_method
      ).compute()
      assert 0.1 < a < 0.9
      assert 0.1 < b < 0.9
      assert a < b
  
file_path: dask/dask/array/tests/test_percentiles.py
imports: from __future__ import annotations
  import pytest
  import numpy
  import dask.array
  from dask.array.utils import assert_eq, same_keys
label_desc: Use image node_id 6 for calling a global function with example usage: test_unknown_chunk_sizes(internal_method) without return types