code: def _top_idx(source, k):
      return torch.topk(source, k=k, dim=0)[1]
  
imports: from deepspeed.utils.timer import SynchronizedWallClockTimer
  from deepspeed.utils import logger
  from typing import Callable, Dict, TYPE_CHECKING, Any, Optional, Tuple
  import torch
  from torch import Tensor
  from torch.nn import Module
  import torch.nn.functional
  from deepspeed.utils import groups
  from .mappings import drop_tokens, gather_tokens
  from deepspeed import comm
label_desc: Use image node_id 5 for calling a global function with example usage: _top_idx(source, k) and returns: torch