code: def test_euler(self):
      ac = np.eye(2)
      bc = 0.5 * np.ones((2, 1))
      cc = np.array([[0.75, 1.0], [1.0, 1.0], [1.0, 0.25]])
      dc = np.array([[0.0], [0.0], [-0.33]])
  
      dt_requested = 0.5
  
      ad_truth = 1.5 * np.eye(2)
      bd_truth = 0.25 * np.ones((2, 1))
      cd_truth = np.array([[0.75, 1.0], [1.0, 1.0], [1.0, 0.25]])
      dd_truth = dc
  
      ad, bd, cd, dd, dt = c2d(
          (ac, bc, cc, dc), dt_requested, method="euler"
      )
  
      assert_array_almost_equal(ad_truth, ad)
      assert_array_almost_equal(bd_truth, bd)
      assert_array_almost_equal(cd_truth, cd)
      assert_array_almost_equal(dd_truth, dd)
      assert_almost_equal(dt_requested, dt)
  
imports: from __future__ import division, print_function, absolute_import
  import numpy
  from numpy.testing import assert_array_almost_equal, assert_almost_equal, assert_allclose, assert_equal
  import warnings
  from scipy.signal import cont2discrete
  from scipy.signal import dlsim, ss2tf, ss2zpk, lsim2, lti
label_desc: Use image node_id 3 for calling the TestC2D obj's underlying member method code with example usage: obj.test_euler() without return types