code: def test_keras_net_layers(self):
      x1 = Input(shape=(8,))
      x2 = Input(shape=(6,))
      y1 = Dense(10)(x1)
      y2 = Dense(10)(x2)
      model = Model([x1, x2], [y1, y2])
      assert len(model.layers) == 4
  
imports: import pytest
  import shutil
  from pyspark.sql.types import *
  from pyspark.sql.functions import lit
  from bigdl.dllib.feature.common import ChainedPreprocessing
  from bigdl.dllib.nncontext import *
  from bigdl.dllib.feature.image import *
  from bigdl.dllib.keras.layers import *
  from bigdl.dllib.keras.models import *
  from bigdl.dllib.nnframes import *
  from test.bigdl.test_zoo_utils import ZooTestCase
label_desc: Use image node_id 9 for calling the TestSimpleIntegration obj's underlying member method code with example usage: obj.test_keras_net_layers() without return types