using System;

public class BankAccount {

   private double interestRate;
   private string owner;
   private double balance;

   // ...

   public void Withdraw (double amount) {
      if (!AccountOK)
        ComplainAboutNonValidAccount();
      else if (!this.EnoughMoney(amount))
        ComplainAboutMissingMoney();
      else
        balance -= amount;
   }

   public void Deposit (double amount) {
      if (amount >= 10000000)
        CheckIfMoneyHaveBeenStolen();
      else if (!AccountOK)
        ComplainAboutNonValidAccount();
      alse balance += amount;
   }
}   

public class Client{

  public static void Main(){

    BankAccount ba = new BankAccount("Peter");

    if (ba.AccountOK && ba.EnoughMoney(1000))
      ba.WithDraw(1000);
    else
      WithdrawingProblems("...");
    if (!ba.AccountOK)
      MajorProblem("...");
    if (ba.Balance <= 0)
      BankAccountOverdrawn(ba);

    ...
  
    if (ba.AccountOK)
      ba.Deposit(1500);
    if (!ba.AccountOK)
      MajorProblem("...");

  }
}