syntax_data: {"ast_node_type":"other","tokens":[{"end":96,"kind":"keyword","start":0,"text":"a_src.and_then(|a_src|"}]}
source_snippet:                 a_src.and_then(|a_src| a.transitions.get(&a_src)).unwrap_or(&empty_transitions);
context_before:             let a_transitions =
context_after:             let b_transitions =