@classmethod
def reserve_subnet_cidr(cls, addr, **ipnetwork_kwargs):
    """Reserve given subnet CIDR making sure it is not used by create_subnet

        :param addr: the CIDR address to be reserved
        It can be a str or netaddr.IPNetwork instance

        :param **ipnetwork_kwargs: optional netaddr.IPNetwork constructor
        parameters
        """
    if not cls.try_reserve_subnet_cidr(addr, **ipnetwork_kwargs):
        raise ValueError('Subnet CIDR already reserved: %r'.format(addr))
