syntax_data: {"ast_node_type":"other","tokens":[{"end":56,"kind":"keyword","start":0,"text":"candidate.subcandidates.retain_mut(|candidate|"}]}
source_snippet:         candidate.subcandidates.retain_mut(|candidate| {
context_before:         let false_edge_start_block = candidate.subcandidates[0].false_edge_start_block;
context_after:             if candidate.extra_data.is_never {