(downstream_domain, upstream_app_id, use_upstream_app_id=True)
return downstream_ids[0]
:param downstream_domain: name of the downstream domain
    :param upstream_app_id: app._id of application in upstream domain
    :param use_upstream_app_id: whether to search for downstream app based on upstream_app_id or family_id
    DEPRECATED: family_id is deprecated and will be removed. If calling this method, try to use upstream_app_id
:param downstream_domain: name of the downstream domain
    :param upstream_app_id: app._id of application in upstream domain
    :param use_upstream_app_id: whether to search for downstream app based on upstream_app_id or family_id
    DEPRECATED: family_id is deprecated and will be removed. If calling this method, try to use upstream_app_id
: param downstream_domain : name of the downstream domain : param upstream_app_id : app . _id of application in upstream domain : param use_upstream_app_id : whether to search for downstream app based on upstream_app_id or family_id DEPRECATED : family_id is deprecated and will be removed . If calling this method try to use upstream_app_id
def get_downstream_app_id(downstream_domain, upstream_app_id, use_upstream_app_id=True):
    """
    :param downstream_domain: name of the downstream domain
    :param upstream_app_id: app._id of application in upstream domain
    :param use_upstream_app_id: whether to search for downstream app based on upstream_app_id or family_id
    DEPRECATED: family_id is deprecated and will be removed. If calling this method, try to use upstream_app_id
    """
    downstream_ids = get_downstream_app_id_map(
        downstream_domain,
        use_upstream_app_id=use_upstream_app_id
    )[upstream_app_id]
    if not downstream_ids:
        return None
    if len(downstream_ids) > 1:
        raise MultipleDownstreamAppsError
    return downstream_ids[0]
def get_downstream_app_id ( downstream_domain , upstream_app_id , use_upstream_app_id = True ) : downstream_ids = get_downstream_app_id_map ( downstream_domain , use_upstream_app_id = use_upstream_app_id ) [ upstream_app_id ] if not downstream_ids : return None if len ( downstream_ids ) > 1 : raise MultipleDownstreamAppsError return downstream_ids [ 0 ]