title: How to implement Merge from Keras.layers
body: <p>I have been trying to merge the following sequential models but haven't been able to. Could somebody please point out my mistake, thank you.</p>
  
  <p>The code compiles while using"merge" but give the following error "TypeError: 'module' object is not callable"
  However it doesn't even compile while using "Merge"</p>
  
  <p>I am using keras version 2.2.0 and python 3.6</p>
  
  <pre><code>from keras.layers import merge
  def linear_model_combined(optimizer='Adadelta'):    
      modela = Sequential()
      modela.add(Flatten(input_shape=(100, 34)))
      modela.add(Dense(1024))
      modela.add(Activation('relu'))
      modela.add(Dense(512))
  
      modelb = Sequential()
      modelb.add(Flatten(input_shape=(100, 34)))
      modelb.add(Dense(1024))
      modelb.add(Activation('relu'))
      modelb.add(Dense(512))
  
      model_combined = Sequential()
  
      model_combined.add(Merge([modela, modelb], mode='concat'))
  
      model_combined.add(Activation('relu'))
      model_combined.add(Dense(256))
      model_combined.add(Activation('relu'))
  
      model_combined.add(Dense(4))
      model_combined.add(Activation('softmax'))
  
      model_combined.compile(loss='categorical_crossentropy', optimizer=optimizer, metrics=['accuracy'])
  
      return model_combined
  </code></pre>