syntax_data: {"ast_node_type":"other","tokens":[{"end":58,"kind":"keyword","start":0,"text":"hir::CoroutineDesugaring::Gen,"}]}
source_snippet:                             hir::CoroutineDesugaring::Gen,
context_before:                         hir::CoroutineKind::Desugared(
context_after:                             hir::CoroutineSource::Closure,