def add_member(self, host_name, hostgroup_name):
        """Add a host string to a hostgroup member
        if the host group do not exist, create it

        :param host_name: host name
        :type host_name: str
        :param hostgroup_name:hostgroup name
        :type hostgroup_name: str
        :return: None
        """
        hostgroup = self.find_by_name(hostgroup_name)
        if not hostgroup:
            hostgroup = Hostgroup({'hostgroup_name': hostgroup_name,
                                   'alias': hostgroup_name,
                                   'members': host_name})
            self.add(hostgroup)
        else:
            hostgroup.add_members(host_name)
Add a host string to a hostgroup member
        if the host group do not exist, create it

        :param host_name: host name
        :type host_name: str
        :param hostgroup_name:hostgroup name
        :type hostgroup_name: str
        :return: None