Sieve of Eratosthenes by Python

prime.py

import math

NUMBER = 1000

def prime_bool_list(num):
    num_list = [True] * num
    num_list[0] = num_list[1] = False
    limit_sqrt = math.sqrt(num)

    for count in xrange(2,num):
        if count >= limit_sqrt:
            return [i for i, b in enumerate(num_list) if b == True]

        for composite in range(count ** 2, num, count):
            num_list[composite] = False

print prime_bool_list(NUMBER)