Simple python prime generator

primes.py

def next_prime():
    """Prime generator.
    >>> import primes
    >>> a = primes.next_prime()
    >>> a.next()
    2
    >>> a.next()
    3
    """
    def is_prime(n):
        for i in range(2, n):
            if n % i == 0:
                return False
        return True

    i = 2
    while True:
        if is_prime(i):
            yield i
        i += 1