public func validate_memo(memo : ?T.Memo) : BoolChecks if a transaction memo is valid
public func is_too_old(token : T.TokenData, created_at_time : Nat64) : BoolChecks if the created_at_time of a transfer request is before the accepted time range
public func is_in_future(token : T.TokenData, created_at_time : Nat64) : BoolChecks if the created_at_time of a transfer request has not been reached yet relative to the canister's time.
public func deduplicate(token : T.TokenData, tx_req : T.TransactionRequest) : Result.Result<(), Nat>Checks if there is a duplicate transaction that matches the transfer request in the main canister.
If a duplicate is found, the function returns an error (#err) with the duplicate transaction's index.
public func validate_fee(token : T.TokenData, opt_fee : ?T.Balance) : BoolChecks if a transfer fee is valid
public func validate_request(token : T.TokenData, tx_req : T.TransactionRequest) : Result.Result<(), T.TransferError>Checks if a transfer request is valid