code: def test_energy_function(self):
      input_vector = np.array([[1, 0, 0, 1, 1, 0, 0]])
      dhnet = algorithms.DiscreteHopfieldNetwork()
      dhnet.train(input_vector)
  
      self.assertEqual(-21, dhnet.energy(input_vector))
      self.assertEqual(
          3, dhnet.energy(np.array([[0, 0, 0, 0, 0, 0, 0]]))
      )
      self.assertEqual(
          -21, dhnet.energy(np.array([0, 1, 1, 0, 0, 1, 1]))
      )
  
      # Test energy calculatin for the 1d array
      self.assertEqual(3, dhnet.energy(np.array([0, 0, 0, 0, 0, 0, 0])))
  
      np.testing.assert_array_almost_equal(
          np.array([-21, 3]),
          dhnet.energy(
              np.array(
                  [
                      [0, 1, 1, 0, 0, 1, 1],
                      [0, 0, 0, 0, 0, 0, 0],
                  ]
              )
          ),
      )
  
file_path: neupy/tests/algorithms/memory/test_discrete_hn.py
imports: import numpy
  from neupy import algorithms
  from algorithms.memory.data import zero, one, two, half_one, half_zero, half_two
  from base import BaseTestCase
label_desc: Use image node_id 6 for calling the DiscreteHopfieldNetworkTestCase obj's underlying member method code with example usage: obj.test_energy_function() without return types