USING PYTHON - Write a program that calls a function that prompts the user to enter a real number. The function should verify that the user entered a valid real number, and should prompt the user to re-enter any invalid input. After a valid real number has been entered, the function should return the number as a number. To test your function, from a main function, call the function two separate times and print the sum of the two numbers returned. Note: Your function must be robust enough to handle all types of input including alphabetic characters without "blowing up". Additional restrictions: For this problem you are NOT allowed to use exception handling or any built-in functions or methods except for input() and print().