code: def test_single_input_for_parallel_layers(self):
      left = layers.Input(10, name="input") >> layers.Sigmoid(5)
      right = left >> layers.Sigmoid(2)
      network = (left | right) >> layers.Concatenate()
  
      self.assertEqual(len(network.input_layers), 1)
  
      input_layer = network.input_layers[0]
      self.assertEqual(input_layer.name, "input")
  
file_path: neupy/tests/layers/graph/test_extra_features.py
imports: from neupy import layers
  from base import BaseTestCase
label_desc: Use image node_id 1 for calling the GraphExtraFeaturesTestCase obj's underlying member method code with example usage: obj.test_single_input_for_parallel_layers() without return types