def _to_equivalence_from_scope(scope):
    """Converts a scope into an equivalence

    Args:
        scope: a `pronto.Synonym.scope`

    Returns:
        an equivalence from https://www.hl7.org/fhir/valueset-concept-map-equivalence.html
    """
    try:
        return {
            'BROAD': 'wider',
            'NARROW': 'narrower',
            'EXACT': 'equivalent',
            'RELATED': 'relatedto'
        }[scope]
    except KeyError:
        raise RuntimeError('scope \'%s\' is not supported' % scope)