[Project Euler Problem 10]Summation of primes

def isprime(x):
    r = int(sqrt(x))
    if x%2 == 0:
        return 0
    for i in range(3, r+1, 2):
        if x%i == 0:
            return 0
    return 1

rst = 0
for i in range(1, 2*10**6):
    if isprime(i):
        rst += i
print rst

Problem 3에서 사용한 isprime함수 재탕