code: def mask_2x2():
      """
      Generates 2x2 mask (doesn't have the 3rd dimension compare to an image).
  
      Returns
      -------
      out : ndarray
          2x2 mask, uint8
      """
      return np.array([[1, 0], [0, 1]]).reshape((2, 2)).astype(np.uint8)
  
file_path: solt/tests/fixtures.py
imports: import pytest
  import numpy
  from .utils import gen_gs_img_black_edge
label_desc: Use image node_id 2 for calling a global function with example usage: mask_2x2() and returns: np