def __init__(self, total_iter_length, final_ratio, warmup_steps=0) -> None:
        """
        Customized iteration-wise exponential scheduler.
        Re-calculate for every step, to reduce error accumulation

        Args:
            total_iter_length (int): Expected total iteration number
            final_ratio (float): Expected LR ratio at n_iter = total_iter_length
        """
        self.total_length = total_iter_length
        self.effective_length = total_iter_length - warmup_steps
        self.final_ratio = final_ratio
        self.warmup_steps = warmup_steps

        Customized iteration-wise exponential scheduler.
        Re-calculate for every step, to reduce error accumulation

        Args:
            total_iter_length (int): Expected total iteration number
            final_ratio (float): Expected LR ratio at n_iter = total_iter_length
        
src/util/lr_scheduler.py