syntax_data: {"ast_node_type":"variable","tokens":[{"end":48,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let m = match tcx.as_lang_item(trait_did)? {
context_before: fn op_trait_as_method_name(tcx: TyCtxt<'_>, trait_did: DefId) -> Option<&'static str> {
context_after:         LangItem::Add => "add",