{"ast_node_type":"function","tokens":[{"end":51,"kind":"keyword","start":0,"text":"fn"}]}
    fn fn_direct_ctr() -> Self { unimplemented!() }
    fn fn_ctr_with_args(input: T) -> Foo<T> { unimplemented!() }
    fn fn_ctr_wrapped() -> Option<Self> { unimplemented!() }