LaTeX3 puzzles:
1. Extending the analogy of having `\cs_show:c` and not `\show:c`, why don't we have `\cs_use:c`? `\use:c` doesn't really fit well in the suffixed functions. Well, it may make sense because of the `:c`, but that was an option for `\show` too. Maybe because `\cs_show:N` was needed, `\cs_show:c` was just generated as a variant and since `\cs_use:N` was never required, `\use:c` sufficed, but it still feels like an odd person out.
2. Why don't we have `\bool_(g)false_new:N` following the `gclear` and `gzero` paradigm?