[Users] Use of append_branch

[Douglas Garstang]

How can I call append branch and use a variable name in the user port (ie the user for which this message is addressed) of the URI?

_ALL_ the examples have something like:

append_branch("sip:nonsense at 192.168.2.16:5064");

which is completely useless. I need to call append_branch and have the user portion of the uri inserted.
Something like:

append_branch("sip:$to_user at 192.168.2.16:5064");

How can I do this?

Doug.