code: def test_sofm_training_with_4d_grid(self):
      sofm = algorithms.SOFM(
          n_inputs=4,
          n_outputs=8,
          features_grid=(2, 2, 2),
          verbose=False,
      )
  
      data = np.concatenate([X, X], axis=1)
  
      sofm.train(data, epochs=1)
      error_after_first_epoch = sofm.errors.train[-1]
  
      sofm.train(data, epochs=9)
      self.assertLess(sofm.errors.train[-1], error_after_first_epoch)
  
imports: import math
  import numpy
  from neupy import algorithms
  from neupy.exceptions import WeightInitializationError
  from neupy.algorithms.competitive import sofm
  from neupy.algorithms.competitive.neighbours import gaussian_df
  from base import BaseTestCase
label_desc: Use image node_id 6 for calling the SOFMTestCase obj's underlying member method code with example usage: obj.test_sofm_training_with_4d_grid() without return types