Using Keras's Sequential API to add classification head on top of InceptionV3 base model.

adding_classification_head.py

def build_model():
    
    # Using Sequential API to stack up the layers
    model = keras.Sequential([
        base_model,
        keras.layers.GlobalAveragePooling2D(),
        keras.layers.Dense(metadata.features['label'].num_classes, 
                           activation='softmax')
    ])
    
    # Compile the model to configure training parameters
    model.compile(optimizer='adam',
                  loss='sparse_categorical_crossentropy',
                  metrics=['accuracy'])
    return model

inception_model = build_model()