Function build_levels_sexp 

pub fn build_levels_sexp(levels: &[&str]) -> SEXP

Build a levels STRSXP of UTF-8 CHARSXPs.

Level names are not interned as R symbols, so names built from data stay collectable. The returned STRSXP is NOT protected - caller must protect or preserve it.

Panics

If a level name contains a null byte.