syntax_data: {"ast_node_type":"other","tokens":[{"end":67,"kind":"keyword","start":0,"text":"scrutinee:"}]}
source_snippet:                             scrutinee: self.mirror_expr(scrutinee),
context_before:                         match_data: Box::new(LoopMatchMatchData {
context_after:                             arms: arms.iter().map(|a| self.convert_arm(a)).collect(),