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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def to_routing_header(params):
 """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. """

    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="/",
    )