def factors(nraw):
    """
    function for getting the primes factors of a number.

    This is supposed to help with figuring out the file format.
    I'm sure there's a better method, but it doesn't matter too much.
    """
    result = []
    n = nraw
    for i in range(2, n + 1):
        s = 0
        while n % i == 0:
            n = n / float(i)
            s += 1
        if s > 0:
            for k in range(s):
                result.append(i)
            if n == 1:
                return result
    return [nraw]
