{"ast_node_type":"variable","tokens":[{"end":63,"kind":"keyword","start":0,"text":"let"}]}
        let callable_ty = self.resolve_ty_shallow(callable_ty);
    fn register_obligations_for_call(&mut self, callable_ty: &Ty) {
        if let TyKind::FnDef(fn_def, parameters) = callable_ty.kind(Interner) {