syntax_data: {"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"assert!(leaf_candidate.match_pairs.is_empty());"}]}
source_snippet:             assert!(leaf_candidate.match_pairs.is_empty());
context_before:             // but extending can also recycle any existing vector capacity.
context_after:             leaf_candidate.match_pairs.extend(remaining_match_pairs.iter().cloned());