code: def test_is_skew_sym(rndstate):
      A = rndstate.randn(n, n)
      assert is_skew_sym(A - A.T)
      assert not is_skew_sym(np.eye(n))
      assert not is_skew_sym(A + A.T)
      assert not is_skew_sym(np.ones((n, n + 1)))
  
file_path: pyRiemann/tests/test_utils_test.py
imports: import numpy
  import pytest
  from pyriemann.utils.test import is_square, is_sym, is_skew_sym, is_real, is_real_type, is_hermitian, is_pos_def, is_pos_semi_def, is_sym_pos_def, is_sym_pos_semi_def, is_herm_pos_def, is_herm_pos_semi_def
label_desc: Use image node_id 3 for calling a global function with example usage: test_is_skew_sym(rndstate) without return types