syntax_data: {"ast_node_type":"variable","tokens":[{"end":53,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let args = tcx.mk_args(&[tcx.types.unit.into()]);
context_before:     let poll_def_id = tcx.require_lang_item(LangItem::Poll, source_info.span);
context_after:     let val = Operand::Constant(Box::new(ConstOperand {