retraining tensorflow and model definition of dense layers: why x is not overridden?

Question

Good evening everyone

I don't understand why the value of x is not overridden. Isn't x reassigned?

x = layers.Flatten()(last_output)
x = layers.Dense(1024, activation='relu')(x)
x = layers.Dropout(0.2)(x)                  
x = layers.Dense(1, activation='sigmoid')(x)