[Serusers] Getting contact URI

[Tom Gaudasinski]

Greetings,
    I have two questions. What function() would i use to get a bool back 
indicating whether a certain user is in the usrloc given i only know the 
'username' field of the usrloc table? Secondly how can I get the contact 
URI/IP address of a user given again I only know the 'username' field of 
the usrloc table?; this will be used in a forward() statement.

Thank you.