Function same_name 

pub fn same_name(a: &str, b: &str) -> bool

Whether two LET/LAMBDA names are the same: case-insensitive in any script, as in Excel (dług = DŁUG, ß = ẞ). Close to Unicode’s default case folding: lower case, plus the folds lower-casing misses for letters a name may hold (ß/ẞ -> ss, ſ -> s, ς -> σ). Dotless ı stays distinct from i, as outside Turkic languages.