syntax_data: {"ast_node_type":"variable","tokens":[{"end":59,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let mut out = DenseBitSet::new_empty(self.count());
context_before:         assert!(self.superset(input), "{:?} not a superset of {:?}", self.0, input);
context_after:         for (saved_local, local) in self.iter_enumerated() {