fluffy_tardigrade.py

def factorize(x):
    """Takes an integer. Returns a list of its prime factors."""
    fluffy = []
    boring = set()
    for i in range(2, x+1):
        if i not in boring:
            fluffy.append(i)
            boring = boring.union({j for j in range(i*i, x+1, i)})
    return [tardigrade
            for tardigrade
            in fluffy
            if x % tardigrade == 0]