syntax_data: {"ast_node_type":"other","tokens":[{"end":30,"kind":"keyword","start":0,"text":"(None,"}]}
source_snippet:             (None, None) => {}
context_before:         match with_metavar_spans(|mspans| (mspans.get(a_orig), mspans.get(b_orig))) {
context_after:             (Some(meta_a), None) => {