Ask the backend to c14n the uri. See register_uri_backend() for
    details.

    If no backend is found for this uri method, a NotImplementedError
    will be raised.

def c14n_uri(sqluri):
    """
    Ask the backend to c14n the uri. See register_uri_backend() for
    details.

    If no backend is found for this uri method, a NotImplementedError
    will be raised.
    """
    uri_c14n_method = _get_methods_by_uri(sqluri)[METHOD_C14N_URI]
    if not uri_c14n_method:
        return sqluri
    return uri_c14n_method(sqluri)