syntax_data: {"ast_node_type":"other","tokens":[{"end":80,"kind":"keyword","start":0,"text":"ExpnKind::Desugaring(DesugaringKind::Async"}]}
source_snippet:             ExpnKind::Desugaring(DesugaringKind::Async | DesugaringKind::Await),
context_before:             self.ctxt().outer_expn_data().kind,
context_after:         )