syntax_data: {"ast_node_type":"variable","tokens":[{"end":53,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let then_span = this.thir[then].span;
context_before:             ExprKind::If { cond, then, else_opt, if_then_scope } => {
context_after:                 let then_source_info = this.source_info(then_span);