Question:module 'tensorflow' has no attribute 'to_int32'

Question

I run a code in python,

def Mean_IOU_Evaluator(y_true, y_pred):

      prec = []

        for t in np.arange(0.5, 1, 0.05):

                y_pred_ = tf.to_int32(y_pred>t)

            y_pred=tf.dtypes

This error is appeard:

module 'tensorflow' has no attribute 'to_int32'

How can I solve it?