marriage :: [Records] -> Maybe Marriage
marriage rs = S.headMay $ do
    (typed -> Just (M m@(Marriage _ _))) <- childrenBi rs
    return m
marriage :: [Records] -> Maybe Marriage
marriage rs = S.headMay $ do
    (typed -> Just (M m@(Marriage _ _))) <- childrenBi rs
    return m
marriage rs = S.headMay $ do
    (typed -> Just (M m@(Marriage _ _))) <- childrenBi rs
    return m