packagexeth// Frontend should be implemented by users of XEth. Its methods are// called whenever XEth makes a decision that requires user input.typeFrontendinterface{// UnlockAccount is called when a transaction needs to be signed// but the key corresponding to the transaction's sender is// locked.//// It should unlock the account with the given address and return// true if unlocking succeeded.UnlockAccount(address[]byte)bool// This is called for all transactions inititated through// Transact. It should prompt the user to confirm the transaction// and return true if the transaction was acknowledged.//// ConfirmTransaction is not used for Call transactions// because they cannot change any state.