{"ast_node_type":"other","tokens":[{"end":5,"kind":"keyword","start":0,"text":"where"}]}
where
impl<'a, V: Visitor<'a>, T1, T2, T3, T4> Visitable<'a, V> for (T1, T2, T3, T4)
    T1: Visitable<'a, V, Extra = ()>,