E0053: Token missing impl Token block

Every token definition must contain exactly one impl Token { ... } block implementing the built-in Token interface (attach and detach).

Example (error)

token MyToken {
    mint fn mint() {}
}

Fix

Add the impl Token block:

token MyToken {
    mint fn mint() {}
    impl Token {
        fn attach(to: Utxo) {}
        fn detach(source: Utxo) {}
    }
}