model4.py

# Create a MobileNet model
mobile = keras.applications.mobilenet.MobileNet()

# Modify the model
# Choose the 6th layer from the last
x = mobile.layers[-6].output

# Add a dropout and dense layer for predictions
x = Dropout(0.25)(x)
predictions = Dense(7, activation='softmax')(x)

# Create a new model with the new outputs
model = Model(inputs=mobile.input, outputs=predictions)

# Prevent everything except the last 23 layers from being trained
for layer in model.layers[:-23]:
    layer.trainable = False