code: def test_matrix_scalar(self):
      r = np.r_["r", [1, 2], 3]
      assert_equal(type(r), np.matrix)
      assert_equal(np.array(r), [[1, 2, 3]])
  
imports: import pytest
  import textwrap
  import warnings
  import numpy
  from numpy.testing import assert_, assert_equal, assert_raises, assert_raises_regex, assert_array_equal, assert_almost_equal, assert_array_almost_equal
label_desc: Use image node_id 2 for calling the TestConcatenatorMatrix obj's underlying member method code with example usage: obj.test_matrix_scalar() without return types