syntax_data: {"ast_node_type":"function","tokens":[{"end":59,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let poll_fn = Operand::Constant(Box::new(ConstOperand {
context_before:     let poll_fn = Ty::new_fn_def(tcx, poll_fn, [fut_ty]);
context_after:         span: DUMMY_SP,