Specify trainable false for layers in sequential model?

TensorFlow Special Interest Groups TF.js
1

I have noticed we can do this as in Python:

const sequential = tf.sequential()
// add layer 1, 2 3...

// now freeze the layers
sequential.trainable =  false

// and reuse it in another model
tf.model({inputs:sequential.inputs, outputs})

Is it possible to do it using sequential only? For example:

const sequential = tf.sequential()

// add layers like

sequential.layers.add({...})

sequential.trainable =  false

// add now trainable layers
sequential.layers.add({...})
sequential.layers.add({...})

This is useful if the first sequential layers will use weights loaded from elsewhere.