Function logos_text_run_through 

pub fn logos_text_run_through(s: &str, first: i64, last: i64) -> &str

The text a counted loop produces when it copies bytes first through last of s into a sequence and reads them back with text_from_bytes: the bytes under logos_run_through, and the stop text_from_bytes makes when they do not form UTF-8. A slice of text is text exactly when both of its ends fall between characters, so the common case costs two boundary checks.