/// The type of token identifiers.
///
/// This in-protocol identifier is used to distinguish between different tokens, and to associate
/// token accounts with the 'owner' of a particular token.
///
/// The 'owner' of a token supervises the behavior of accounts whose balance is stored in that
/// token, and may use a snapp proof or other authorization to ensure that certain invariants are
/// satisfied when the supervised accounts are updated.
pub type TokenID = u64;