syntax_data: {"ast_node_type":"variable","tokens":[{"end":55,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let val = Operand::Constant(Box::new(ConstOperand {
context_before:     let args = tcx.mk_args(&[tcx.types.unit.into()]);
context_after:         span: source_info.span,