syntax_data: {"ast_node_type":"variable","tokens":[{"end":55,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let scrut = scrutinee.map(|id| &self.thir[id]);
context_before:         assert!(self.let_source != LetSource::None);
context_after:         if let LetSource::PlainLet = self.let_source {