{"ast_node_type":"other","tokens":[{"end":95,"kind":"keyword","start":0,"text":"ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef::erase_self_ty(tcx,"}]}
        ty::ExistentialPredicate::Trait(ty::ExistentialTraitRef::erase_self_ty(tcx, trait_ref))
    let principal_pred = poly_trait_ref.map_bound(|trait_ref| {
    });