Macro vstd::assert_multisets_equal_internal

macro_rules! assert_multisets_equal_internal {
    (::builtin::spec_eq($m1:expr, $m2:expr)) => { ... };
    (::builtin::spec_eq($m1:expr, $m2:expr), $k:ident $( : $t:ty )? => $bblock:block) => { ... };
    (crate::builtin::spec_eq($m1:expr, $m2:expr)) => { ... };
    (crate::builtin::spec_eq($m1:expr, $m2:expr), $k:ident $( : $t:ty )? => $bblock:block) => { ... };
    ($m1:expr, $m2:expr $(,)?) => { ... };
    ($m1:expr, $m2:expr, $k:ident $( : $t:ty )? => $bblock:block) => { ... };
}