code: def test_impute_value(test_data):
      """fast_knn using standard idw"""
      data = test_data(SHAPE, 0, 2)
      imputed = impy.fast_knn(data, k=2)
      assert np.isclose(imputed[0, 2], 8.38888888888889)
  
imports: import functools
  import numpy
  import impyute
  from impyute.ops.testing import return_na_check
label_desc: Use image node_id 2 for calling a global function with example usage: test_impute_value(test_data) without return types