code: def test_node_repr(self):
      node_a = NeuronNode(1)
      self.assertEqual(str(node_a), "<NeuronNode error=0.0>")
  
      node_a.error = 1
      self.assertEqual(str(node_a), "<NeuronNode error=1.0>")
  
      node_a.error = 3.141592654
      self.assertEqual(str(node_a), "<NeuronNode error=3.141593>")
  
file_path: neupy/tests/algorithms/competitive/test_growing_neural_gas.py
imports: import pickle
  import numpy
  import matplotlib.pyplot
  from sklearn.datasets import make_blobs
  from neupy import algorithms
  from neupy.algorithms.competitive.growing_neural_gas import NeuralGasGraph, NeuronNode
  from base import BaseTestCase
label_desc: Use image node_id 2 for calling the NeuralGasGraphTestCase obj's underlying member method code with example usage: obj.test_node_repr() without return types