def setup_basic_filtering(self, instance, network_info):
        self.nwfilter.setup_basic_filtering(instance, network_info)
        if not self.basicly_filtered:
            LOG.debug(_('iptables firewall: Setup Basic Filtering'))
            self.refresh_provider_fw_rules()
            self.basicly_filtered = True
Read a character in nonblocking mode, if no characters are present in the buffer, return an empty string
dataset/ETHPy150Open nii-cloud/dodai-compute/nova/virt/libvirt/firewall.py/IptablesFirewallDriver.setup_basic_filtering--crossover with--dataset/ETHPy150Open pindexis/qfc/qfc/readchar.py/read_char_no_blocking