What does "formally safe" mean for you here? Are you talking about something like SEL4 that is formally verified? If yes, I wonder how many SW's are out that th

What does "formally safe" mean for you here? Are you talking about something like SEL4 that is formally verified? If yes, I wonder how many SW's are out that that are actually formally verified. Also, the problem of formal verification lies not in the language but in the code itself, right? So what would the problem be with Rust or Go?