The Rust-test implements the traits Add, Sub, Mul by value. This makes the few references less important in the total test. The ergonomics argument is motivated

The Rust-test implements the traits Add, Sub, Mul by value. This makes the few references less important in the total test. The ergonomics argument is motivated by using these traits. Otherwise, references would have had the same ergonomics. But also, the struct is 3x32 bits, and Rust auto-implements the Copy-trait for it. It is barely larger than u64, which is the size of the reference. But life is only simpler when Copy and Clone can be auto-implemented.