.swift

 func transactionsBy(drivingLicenseNumber :String) -> [Transaction] {
        
        var transactions = [Transaction]()
        
        self.blocks.forEach { block in
            
            block.transactions.forEach { transaction in
                
                if transaction.driverLicenseNumber == drivingLicenseNumber.sha1Hash() {
                    transactions.append(transaction)
                }
            }
        }
        
        return transactions
        
    }