code: def assert_invalid_distance_function(
      self, func, vector, weight, expected, decimal=6
  ):
      np.testing.assert_array_almost_equal(
          func(vector, weight), expected, decimal=decimal
      )
  
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 1 for calling the SOFMDistanceFunctionsTestCase obj's underlying member method code with example usage: obj.assert_invalid_distance_function(func, vector, weight, expected, decimal) without return types