def is_valid_chain(self, chain):
        # Verify chain existence. Requires valid table first
        if not chain in self.current_table.iterkeys():
            self.writeln("%s: No chain/target/match by that name." % command_iptables.APP_NAME)
            self.exit()
            return False

        # Exists
        return True
dataset/ETHPy150Open basilfx/kippo-extra/kippo_extra/commands/iptables.py/command_iptables.is_valid_chain/original