syntax_data: {"ast_node_type":"other","tokens":[{"end":44,"kind":"keyword","start":0,"text":"Some(arm_span.to(comma))"}]}
source_snippet:                     Some(arm_span.to(comma))
context_before:                 if let Some(comma) = sm.span_look_ahead(with_whitespace, ",", Some(1)) {
context_after:                 } else {