syntax_data: {"ast_node_type":"variable","tokens":[{"end":23,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let arm = Arm {
context_before:     fn convert_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) -> ArmId {
context_after:             pattern: self.pattern_from_hir(&arm.pat),