code: def encode(self) -> str:
      token_json = json.dumps(
          {
              "index": self.index,
          }
      )
      encoded_token_bytes = base64.b64encode(bytes(token_json, "utf-8"))
      return encoded_token_bytes.decode("utf-8")
  
imports: import base64
  import functools
  import inspect
  import json
  import logging
  import posixpath
  import re
  import textwrap
  import warnings
  from typing import List, Optional
  from urllib.parse import urlparse
  from mlflow.environment_variables import MLFLOW_GATEWAY_URI
  from mlflow.exceptions import MlflowException
  from mlflow.gateway.constants import MLFLOW_AI_GATEWAY_MOSAICML_CHAT_SUPPORTED_MODEL_PREFIXES
  from mlflow.utils.uri import append_to_uri_path
label_desc: Use image node_id 4 for calling the SearchRoutesToken obj's underlying member method code with example usage: obj.encode() and returns: encoded_token_bytes