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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def linkify_s_by_hst(self, hosts):
 """Link services with their parent host :param hosts: Hosts to look for simple host :type hosts: alignak.objects.host.Hosts :return: None """

        for serv in self:
            # If we do not have a host_name, we set it as
            # a template element to delete. (like Nagios)
            if not hasattr(serv, 'host_name'):
                serv.host = None
                continue
            try:
                hst_name = serv.host_name
                # The new member list, in id
                hst = hosts.find_by_name(hst_name)
                # Let the host know we are his service
                if hst is not None:
                    serv.host = hst.uuid
                    hst.add_service_link(serv.uuid)
                else:  # Ok, the host do not exists!
                    err = "Warning: the service '%s' got an invalid host_name '%s'" % \
                          (serv.get_name(), hst_name)
                    serv.configuration_warnings.append(err)
                    continue
            except AttributeError:
                pass