docstr: Load optimizer from sharded checkpoint.
code: def load_sharded_optimizer(
      self,
      optimizer: Optimizer,
      index_file_path: str,
      prefix: Optional[str] = None,
  ):
      """
      Load optimizer from sharded checkpoint.
      """
      assert isinstance(
          optimizer, OptimizerWrapper
      ), "Please boost the optimizer before loading!"
      super().load_sharded_optimizer(
          optimizer.unwrap(), index_file_path, prefix
      )
  
imports: from typing import Callable, Iterator, List, Optional, Tuple
  import torch.nn
  from torch.nn.parallel import DistributedDataParallel
  from torch.optim import Optimizer
  from torch.optim.lr_scheduler import _LRScheduler
  from torch.utils.data import DataLoader
  from colossalai.checkpoint_io import CheckpointIO, GeneralCheckpointIO
  from colossalai.cluster import DistCoordinator
  from colossalai.interface import ModelWrapper, OptimizerWrapper
  from .dp_plugin_base import DPPluginBase
label_desc: Use image node_id 10 for calling the TorchDDPCheckpointIO obj's underlying member method code with example usage: obj.load_sharded_optimizer(optimizer, index_file_path, prefix) without return types