code: def test_masked_arr_returned(im, im_mask):
      """Test for return of masked_array type."""
  
      masked = mask_pixels(im, im_mask, vals=[0])
      assert np.ma.is_masked(masked)
  
file_path: earthpy/earthpy/tests/test_mask.py
imports: import numpy
  from earthpy.mask import mask_pixels
  import pytest
label_desc: Use image node_id 4 for calling a global function with example usage: test_masked_arr_returned(im, im_mask) without return types