code: def to_routing_header(params):
      
      if sys.version_info[0] < 3:
          # Python 2 does not have the "safe" parameter for urlencode.
          return urlencode(params).replace("%2F", "/")
      return urlencode(
          params,
          # Per Google API policy (go/api-url-encoding), / is not encoded.
          safe="/",
      )
docs: Returns a routing header string for the given request parameters.
  
      Args:
          params (Mapping[str, Any]): A dictionary containing the request
              parameters used for routing.
  
      Returns:
          str: The routing header string.