syntax_data: {"ast_node_type":"variable","tokens":[{"end":48,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let expr_span = self.thir[expr_id].span;
context_before:     ) -> BlockAnd<()> {
context_after:         let scrutinee = unpack!(block = self.lower_scrutinee(block, expr_id, expr_span));