pub fn verify_proof<Hashing, Key, Value>(
    root: &Hashing::Out,
    proof: &[u8],
    key: &Key,
    value: &Value,
) -> Result<(), DispatchError>where
    Hashing: Hasher,
    Key: Encode,
    Value: Encode,Expand description
Verify the existence of key and value in a given trie root and proof.