code: def test_sofm_gaussian_df(self):
      actual_output = gaussian_df(np.arange(-3, 4), mean=0, std=1)
      expected_output = np.array(
          [
              0.23873659,
              0.52907781,
              0.8528642,
              1.0,
              0.8528642,
              0.52907781,
              0.23873659,
          ]
      )
      np.testing.assert_array_almost_equal(
          expected_output, actual_output
      )
  
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 2 for calling the SOFMUtilsFunctionTestsCase obj's underlying member method code with example usage: obj.test_sofm_gaussian_df() without return types