syntax_data: {"ast_node_type":"variable","tokens":[{"end":39,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let expr = &this.thir[expr_id];
context_before:         let this = self;
context_after:         debug!("expr_as_rvalue(block={:?}, scope={:?}, expr={:?})", block, scope, expr);