Macro mischief::runtime_token

macro_rules! runtime_token {
    ($name:ident) => { ... };
    (pub $name:ident) => { ... };
    (pub ($($vis:tt)*) $name:ident) => { ... };
    (@impl $name:ident $($vis:tt)*) => { ... };
}

Creates a token with a fresh type that is checked for uniqueness at runtime.