Function grin_wallet::libwallet::internal::keys::retrieve_existing_key

pub fn retrieve_existing_key<T: ?Sized, C, K>(
    wallet: &T, 
    key_id: Identifier, 
    mmr_index: Option<u64>
) -> Result<(Identifier, u32), Error> where
    T: WalletBackend<C, K>,
    C: NodeClient,
    K: Keychain, 

Retrieve an existing key from a wallet