Function reference_trie_root_iter_build 

pub fn reference_trie_root_iter_build<T, I, A, B>(
    input: I,
) -> <T::Hash as Hasher>::Out
where
    T: TrieLayout,
    I: IntoIterator<Item = (A, B)>,
    A: AsRef<[u8]> + Ord + Debug,
    B: AsRef<[u8]> + Debug,