code: def test_2d(self):
      b = np.random.rand(5, 5)
      c = np.random.rand(5, 5)
      d = r_["1", b, c]  # append columns
      assert_(d.shape == (5, 10))
      assert_array_equal(d[:, :5], b)
      assert_array_equal(d[:, 5:], c)
      d = r_[b, c]
      assert_(d.shape == (10, 5))
      assert_array_equal(d[:5, :], b)
      assert_array_equal(d[5:, :], c)
  
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 5 for calling the TestConcatenator obj's underlying member method code with example usage: obj.test_2d() without return types