3. (Suppose that you are traveling to Sweden , where Swedish krona (SEK) is the official currency). A vending machine offers two different products A and B. Product A costs 4 SEK, product B 6 SEK. The customer inserts one coin at a time into the slot. The machine accepts coins in denominations of 1, 5 or 10 SEK. The machine displays the amount available for purchasing products. The machine has three buttons, button A to dispense product A, button B to dispense product B and button C to obtain change. At any time, the customer can press button C to collect her change or amount paid, even if no purchase but the machine only dispenses the corresponding product if the current amount paid is equal to or exceeds the product price. It is possible to make multiple purchases with one payment by using the remaining amount for another purchase (for example inserting a l0 occurred previously. The customer can press buttons A and B at any time, SEK coin and purchasing product A twice and obtain 2 SEK change or for example inserting a 5 SEK coin, purchasing product A, inserting another 5 SEK coin and purchasing product B) 4. Explain why professional software is not just the programs that are developed for a customer 5. Compare between different deploying testing techniques