+ } else if let Some(directive) = cmd.strip_prefix("mark ") {
+ match directive.split_once(':') {
+ None => {
+ return Err(std::io::Error::new(
+ std::io::ErrorKind::InvalidInput,
+ format!("line {line_num}: Mark missing ':'"),
+ ))
+ }
+ Some((col, label)) => self.mark.insert(col.to_owned(), label.to_owned()),
+ };