syntax_data: {"ast_node_type":"other","tokens":[{"end":79,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:         // actually desugar these into two separate `ExistentialPredicate`s. We
context_before:         // is under the same binders (`['a]`) as the `Foo<'a>` bit. However, we
context_after:         // can't enter/exit the "binder scope" twice though, because then we