{"ast_node_type":"other","tokens":[{"end":36,"kind":"keyword","start":0,"text":"//"}]}
    // Allow "E0123" or "0123" form.
fn handle_explain(early_dcx: &EarlyDiagCtxt, registry: Registry, code: &str, color: ColorConfig) {
    let upper_cased_code = code.to_ascii_uppercase();