Recursively calculates the prime factorization of any given number

gistfile1.py

def prime_factorization(inputvalue, sieve = True, primes = None):
    """
    Takes an Integer argument and returns a the prime factorization as a list.
    e.g. prime_factorization(45) => [3, 3, 5]
    
    Optional arguments are 'sieve' and 'primes'; default values are 'True' and
    'None' respectively. Setting sieve to 'False' commits the user to providing
    a set of primes as a list.
    e.g. prime_factorization(45, sieve=False, primes=[3]) => [3, 3]
    """
    if inputvalue in [0, 1, -1]:
        print("only an asshole tries to find the prime factorization of 0 or 1")
        return
    
    negative = False
    if inputvalue < 0:
        negative = True
    
    if sieve:
        candidates = prime_sieve(abs(inputvalue))
    else:
        candidates = primes
    
    factors = []
    
    for prime in candidates:
        if not inputvalue % prime:
            factors.append(prime)
            outvalue = inputvalue / prime
            break
        outvalue = 1
            
    if outvalue != 1:
        factors += prime_factorization(outvalue, sieve = False, primes = candidates)
    
    if negative:
        factors.insert(0, -1)
    
    return factors