def lr_schedule(epoch):
    """Learning Rate Schedule

    Learning rate is scheduled to be reduced after 10, 20, 30, 50 epochs.
    Called automatically every epoch as part of callbacks during training.

    # Arguments
        epoch (int): The number of epochs

    # Returns
        lr (float32): learning rate
    """
    lr = 0.001
    if epoch > 60:
        lr *= 0.0001
    elif epoch > 55:
        lr *= 0.001
    elif epoch > 40:
        lr *= 0.01
    elif epoch > 20:
        lr *= 0.1
    print('Learning rate: ', lr)
    return lr
