Macro generativity::make_guard

macro_rules! make_guard {
    ($name:ident) => { ... };
}

Create a Guard with a unique invariant lifetime (with respect to other trusted/invariant lifetime brands).

Multiple make_guard lifetimes will always fail to unify:

make_guard!(a);
make_guard!(b);
dbg!(a == b); // ERROR (here == is a static check)