syntax_data: {"ast_node_type":"variable","tokens":[{"end":78,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let error_format = if matches.opts_present(&["error-format".to_owned()]) {
context_before:     // `opt_present` because the latter will panic.
context_after:         match matches.opt_str("error-format").as_deref() {