Write python main program and a function that accepts a string as an argument which is aseries of single-digit numbers with nothing separating them. The function should return the sum of all the single digit numbers in the string.

For example, if the user enters 2514, the function should return 12, which is the sum of 2, 5, 1, and 4.

The application should ask the user to enter the string,call the function with the string and then display the sum.