syntax_data: {"ast_node_type":"variable","tokens":[{"end":67,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let typing_env = ty::TypingEnv::non_body_analysis(tcx, def_id);
context_before:     let span = tcx.def_span(def_id);
context_after:     debug!("dtorck_constraint: {:?}", def);