syntax_data: {"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"Some(arg)"}]}
source_snippet:         Some(arg) => Edition::from_str(&arg).unwrap_or_else(|_| {
context_before:     let edition = match matches.opt_str("edition") {
context_after:             early_dcx.early_fatal(format!(