syntax_data: {"ast_node_type":"function","tokens":[{"end":60,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn add_bound_var(&mut self, binder: ty::DebruijnIndex) {
context_before:     /// indicates that `self` refers to something at binding level `binder`
context_after:         let exclusive_binder = binder.shifted_in(1);