Both types have the `From` conversion traits implemented between each other, so in most cases interoperating with APIs using the old type should be as simple as

Both types have the `From` conversion traits implemented between each other, so in most cases interoperating with APIs using the old type should be as simple as doing `(1...4).into()`. And, probably because of the warts of the old types, I haven't seen them used much in APIs, so even that I don't think will happen very often.