pub trait SignedMessageNep {
    const NEP_NUMBER: u32;
}

/// [NEP-461](https://github.com/near/NEPs/pull/461) `prefix_tag`
pub trait OffchainMessage: SignedMessageNep {
    const OFFCHAIN_PREFIX_TAG: u32 = (1u32 << 31) + Self::NEP_NUMBER;
}
impl<T> OffchainMessage for T where T: SignedMessageNep {}

/// [NEP-461](https://github.com/near/NEPs/pull/461) `prefix_tag`
pub trait OnchainMessage: SignedMessageNep {
    const OFFCHAIN_PREFIX_TAG: u32 = (1u32 << 30) + Self::NEP_NUMBER;
}
impl<T> OnchainMessage for T where T: SignedMessageNep {}