def ip_in_net(ip, network):
    ipaddr = int(''.join(['%02x' % int(x) for x in ip.split('.')]), 16)
    netaddr, bits = network.split('/')
    netmask = int(''.join(['%02x' % int(x) for x in netaddr.split('.')]), 16)
    mask = (0xffffffff << (32 - int(bits))) & 0xffffffff
    return (ipaddr & mask) == (netmask & mask)


def human_size(num, suffix=''):
    for unit in ['', 'K', 'M', 'G', 'T', 'P', 'E', 'Z']:
        if abs(num) < 1024.0:
            return "%3.1f %s%s" % (num, unit, suffix)
        num /= 1024.0
    return "%.1f%s%s" % (num, 'Yi', suffix)


class FactoryMixin:
    _instance = None

    @classmethod
    def factory(cls, *args, **kwargs):
        if not cls._instance:
            cls._instance = cls(*args, **kwargs)
        return cls._instance