code: def test_corner_mask(split_collections):
      n = 60
      mask_level = 0.95
      noise_amp = 1.0
      np.random.seed([1])
      x, y = np.meshgrid(np.linspace(0, 2.0, n), np.linspace(0, 2.0, n))
      z = np.cos(7 * x) * np.sin(8 * y) + noise_amp * np.random.rand(
          n, n
      )
      mask = np.random.rand(n, n) >= mask_level
      z = np.ma.array(z, mask=mask)
  
      for corner_mask in [False, True]:
          plt.figure()
          plt.contourf(z, corner_mask=corner_mask)
  
      _maybe_split_collections(split_collections)
  
imports: import datetime
  import platform
  import re
  from unittest import mock
  import contourpy
  import numpy
  from numpy.testing import assert_array_almost_equal, assert_array_almost_equal_nulp, assert_array_equal
  import matplotlib
  from matplotlib import pyplot, rc_context, ticker
  from matplotlib.colors import LogNorm, same_color
  import matplotlib.patches
  from matplotlib.testing.decorators import check_figures_equal, image_comparison
  import pytest
label_desc: Use image node_id 16 for calling a global function with example usage: test_corner_mask(split_collections) without return types