delete :: (Ord k, Ord v) => k -> v -> Multimap k v -> Multimap k v
delete k v (Multimap m) = Multimap $ Map.alter (deleter v) k m
delete :: (Ord k, Ord v) => k -> v -> Multimap k v -> Multimap k v
delete k v (Multimap m) = Multimap $ Map.alter (deleter v) k m
delete k v (Multimap m) = Multimap $ Map.alter (deleter v) k m