Get the next prime number!
You will get a number`n` (>= 0) and your task is to find the next prime number. 
Make sure to optimize your code: there will numbers tested up to about `10^12`.
## Examples
```
5   =>  7
12  =>  13
```
def is_prime(n):
    for i in range(2, int(n ** 0.5) + 1):
        if n % i == 0:
            return False
    return n > 1


def next_prime(n):
    i = n + 1
    while not is_prime(i):
        i += 1
    return i

def is_prime(n):
    for i in range(2, int(n ** 0.5) + 1):
        if n % i == 0:
            return False
    return n > 1


def next_prime(n):
    i = n + 1
    while not is_prime(i):
        i += 1
    return i
