class Account {

    private Double amount;

    public Account(Double amount) {
      this.amount = amount;
    }

    /**
     * Withdraw the price of the item from the account.
     *
     * @param price of the item
     * @return instance of MoneyTransaction
     */
    public MoneyTransaction withdraw(Double price) {<FILL_FUNCTION_BODY>}

    public Double getAmount() {
      return amount;
    }
  }

      if (price > amount) {
        return null;
      }
      return new MoneyTransaction(amount, price);
    
<no_super_class>