ERROR alternate way to add dense layers to pretrained model

Course Q&A TensorFlow Developer Professional Convolutional Neural Networks in TensorFlow
1

C2_W3_Lab_1_transfer_learning.ipynb

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after that below ,rather than creating a variable x and adding the layers to it, i am using the previous original way to add layers to the pretrained model

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but i am getting the error The added layer must be an instance of class Layer.

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This line is the problem

layers.Flatten()(last_output),

Please don’t mix functional and sequential layer styles.
Sequential accepts a list of layers.
Functional style calls the current layer with previous layer as parameter.