Write is_prime(n) that returns True if n is a prime number and False otherwise.
A prime is an integer greater than 1 whose only positive divisors are 1 and itself. Numbers below 2 are never prime.
Examples
Input: n = 2
Output: True
Input: n = 9
Output: False
Input: n = 1
Output: False
Constraints
-10**9 <= n <= 10**9 + 7
Goals
- Return a boolean from a function
- Handle 0, 1 and negatives correctly
- Stop testing at the square root