code: def test_check_if_network_sequential(self):
      network = layers.join(
          layers.Input(10),
          layers.Relu(5),
          layers.Relu(3),
      )
      self.assertTrue(network.is_sequential())
  
      network = layers.join(
          layers.Input(10),
          layers.parallel(
              layers.Relu(5),
              layers.Relu(3),
          ),
          layers.Concatenate(),
      )
      self.assertFalse(network.is_sequential())
  
      network = layers.parallel(
          layers.Relu(5),
          layers.Relu(3),
      )
      self.assertFalse(network.is_sequential())
  
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 3 for calling the GraphExtraFeaturesTestCase obj's underlying member method code with example usage: obj.test_check_if_network_sequential() without return types