AttributeError: module 'tensorflow._api.v2.train' has no attribute 'exponential_decay'

This error occurs when you try to use the `exponential_decay` function from the `tensorflow._api.v2.train` module, but it is not available in the current version of TensorFlow.

To resolve this error, you can try importing the function from the `tensorflow.keras.optimizers.schedules` module instead:

from tensorflow.keras.optimizers.schedules import exponential_decay

Then, you can use the function as follows:

learning_rate_schedule = exponential_decay(initial_learning_rate, decay_steps, decay_rate)

Alternatively, you can try updating your version of TensorFlow to the latest version, which may include the `exponential_decay` function in the `tensorflow.train` module.