Python help.

In mathematics, the notation n! represents the factorial of the nonnegative integer n. The factorial of n is the product of all the nonnegative integers from 1 to n. For example, 7! = 1 times 2 times 3 times 4 times 5 times 6 times 7 = 5040 and 4! = 1 times 2 times 3 times 4 = 24 Write a program that lets the user enter a nonnegative integer and then uses a loop to calculate the factorial of that number. Display the factorial