code: def step(self):
      for idx, p in enumerate(self.param_groups):
          p["lr"] = (
              self.init_lr_groups[idx]
              * (1 - self.curr_iter / self.max_iter) ** self.lr_decay
          )
  
imports: import os
  from math import ceil
  import numpy
  import torch
  import torch.nn.functional
  from torch import nn
label_desc: Use image node_id 2 for calling the PolyLR obj's underlying member method code with example usage: obj.step() without return types