Macro session 

macro_rules! session {
    ($fmt:literal $(, $arg:expr)* $(,)?) => { ... };
}

Available on crate feature sha3 only.

Attaches a 64-byte session identifier to the domain separator.

DomainSeparator::new([0u8; 64])
    .session(session!("example at L{{line!()}}"))
    .instance(b"empty");