code: def assert_mask_equal(m1, m2, err_msg=""):
      """
      Asserts the equality of two masks.
  
      """
      if m1 is nomask:
          assert_(m2 is nomask)
      if m2 is nomask:
          assert_(m1 is nomask)
      assert_array_equal(m1, m2, err_msg=err_msg)
  
imports: import operator
  import numpy
  from numpy import ndarray, float_
  import numpy.core.umath
  import numpy.testing
  from numpy.testing import assert_, assert_allclose, assert_array_almost_equal_nulp, assert_raises, build_err_msg
  from .core import mask_or, getmask, masked_array, nomask, masked, filled
  from unittest import TestCase
label_desc: Use image node_id 14 for calling a global function with example usage: assert_mask_equal(m1, m2, err_msg) without return types