text: # BSD 3-Clause License; see https://github.com/scikit-hep/awkward-1.0/blob/main/LICENSE
  
  
  import pytest  # noqa: F401
  import numpy as np  # noqa: F401
  import awkward as ak  # noqa: F401
  
  
  def test():
      array = ak.Array([[0, 1, 2, 3], [3, 3, 3, 2, 1]])
      is_valid = array != 3
  
      assert array.mask[is_valid].tolist() == [[0, 1, 2, None], [None, None, None, 2, 1]]
  
      assert ak.sort(array.mask[is_valid]).tolist() == [
          [0, 1, 2, None],
          [1, 2, None, None, None],
      ]
      assert ak.argsort(array.mask[is_valid]).tolist() == [
          [0, 1, 2, 3],
          [4, 3, 0, 1, 2],
      ]
  