An integer is said to be **prime** if it's divisible by only 1 and itself.
- For example, 2, 3, 5 and 7 are prime, but 4, 6, 8 and 9 are not.
Write the program that prints all the primes within the user specified range.
1. Define a function `isprime` that determines whether a integer number is prime or not.
- *Hint:* How many of these numbers do you really have to test before being sure that you’ve found all the primes?
2. Use this function in a program that determines and prints all the prime numbers in the user specified range.
- Prompt user to enter upper bound of the range, `maxnum`
- Using function `isprime` check & print all the prime numbers within the range: `[2, maxnum]`
