Get learning rate with exponential decay based on current iteration.

        Args:
            iter (int): Current iteration (starting with 0).

        Returns:
            float: Learning rate

def get_learning_rate(self, iter):
        '''
        Get learning rate with exponential decay based on current iteration.

        Args:
            iter (int): Current iteration (starting with 0).

        Returns:
            float: Learning rate
        '''

        return self.init_lr * (self.gamma ** (iter // self.iter_interval))