docstr: Get the valid length of the chunk's payload.
docstr_tok: ["Get","the","valid","length","of","the","chunk","'s","payload","."]
code: def get_valid_length(self) -> int:
      """Get the valid length of the chunk's payload."""
      if self.keep_gathered:
          return self.utilized_size
      else:
          return self.valid_end
  
imports: from dataclasses import dataclass
  from enum import Enum
  from typing import Dict, List, Optional
  import torch
  import torch.distributed
  from torch.distributed import ProcessGroup
  from colossalai.utils import get_current_device
  from colossalai.utils.device import IS_NPU_AVAILABLE
label_desc: Use image node_id 20 for calling the Chunk obj's underlying member method code with example usage: obj.get_valid_length() and returns: self, self