def _transform_read_gbq_configuration(configuration):
    """
    For backwards-compatibility, convert any previously client-side only
    parameters such as timeoutMs to the property name expected by the REST API.

    Makes a copy of configuration if changes are needed.
    """

    if configuration is None:
        return None

    timeout_ms = configuration.get("query", {}).get("timeoutMs")
    if timeout_ms is not None:
        # Transform timeoutMs to an actual server-side configuration.
        # https://github.com/googleapis/python-bigquery-pandas/issues/479
        configuration = copy.deepcopy(configuration)
        del configuration["query"]["timeoutMs"]
        configuration["jobTimeoutMs"] = timeout_ms

    return configuration

    For backwards-compatibility, convert any previously client-side only
    parameters such as timeoutMs to the property name expected by the REST API.

    Makes a copy of configuration if changes are needed.
    
pandas_gbq/gbq.py