code: def add_knn_mt_args(params):
      knn_params = params.add_argument_group("kNN MT parameters")
  
      knn_params.add_argument(
          "--knn-index",
          type=str,
          help="Optionally use a KNN index during inference to "
          "retrieve similar hidden states and corresponding target tokens.",
          default=None,
      )
      knn_params.add_argument(
          "--knn-lambda",
          type=float,
          help="Interpolation parameter when using KNN index. Default: %(default)s.",
          default=C.DEFAULT_KNN_LAMBDA,
      )
  
imports: import argparse
  import os
  import sys
  import types
  from typing import Any, Callable, Dict, List, Tuple, Optional
  import yaml
  from sockeye.utils import smart_open
  from .None import constants
label_desc: Use image node_id 42 for calling a global function with example usage: add_knn_mt_args(params) without return types