code: def test_bool(self):
      bool_a = [True, False, True, True]
      (int_a,) = np.nonzero(bool_a)
      assert_equal(np.ix_(bool_a)[0], int_a)
  
imports: import pytest
  import numpy
  from numpy.testing import assert_, assert_equal, assert_array_equal, assert_almost_equal, assert_array_almost_equal, assert_raises, assert_raises_regex
  from numpy.lib.index_tricks import mgrid, ogrid, ndenumerate, fill_diagonal, diag_indices, diag_indices_from, index_exp, ndindex, r_, s_, ix_
label_desc: Use image node_id 3 for calling the TestIx_ obj's underlying member method code with example usage: obj.test_bool() without return types