Looking for some clarification / direction on setting up forking.

I have configured clients to use q-value and is stored in location table. I see several examples as described in TM module documentation but does not mention use of lookup() function.

Per registrar documentation-

lookup()

The functions extracts username from Request-URI and tries to find all contacts for the username in usrloc. If there are no such contacts, -1 will be returned. If there are such contacts, Request-URI will be overwritten with the contact that has the highest q value and optionally the rest will be appended to the message (depending on append_branches parameter value).

Append_branch parameter

The parameter controls how lookup function processes multiple contacts. If there are multiple contacts for the given username in usrloc and this parameter is set to 1, Request-URI will be overwritten with the highest-q rated contact and the rest will be appended to sip_msg structure and can be later used by tm for forking.

Does lookup() build the destination set and then I can proceed by doing  t_load_contacts(),  t_next_contacts() and setup failure route? Any direction is appreciated!

Thanks,

-dan