{"ast_node_type":"other","tokens":[{"end":90,"kind":"keyword","start":0,"text":"//"}]}
                // parent) will include `'a` AND all the early- and late-bound vars of the
                // the `late_bound_vars` of the where clause predicate (i.e. this HIR ty's
                // method. But when lowering the RTN type, we just want the list of vars