Write a program that writes all of the prime numbers that
are less than or equal to 40, one per line. Design the
program so that it has one line that defines limit to
be 40, then loops up to limit. Make is so that, if you
change limit to 50, then it will show all of the
prime numbers that are less than or equal to 50.
For this problem, a function
isPrime(n) is available to you, which yields
true if n is prime.