如何在Keras TensorFlow中组合两个预定义的模型？

import tensorflow as tf
from tensorflow.keras.models import Model
from tensorflow.keras.applications import Model1, Model2

model1 = Model1(weights='imagenet')
model2 = Model2(weights='imagenet')

output1 = model1.layers[-1].output
output2 = model2.layers[-1].output

combined_output = tf.keras.layers.Concatenate()([output1, output2])
combined_model = Model(inputs=[model1.input, model2.input], outputs=combined_output)