syntax_data: {"ast_node_type":"other","tokens":[{"end":51,"kind":"keyword","start":0,"text":"scrutinee:"}]}
source_snippet:                 scrutinee: self.mirror_expr(discr),
context_before:             hir::ExprKind::Match(discr, arms, match_source) => ExprKind::Match {
context_after:                 arms: arms.iter().map(|a| self.convert_arm(a)).collect(),