[Samba] How to find all workgroups being used on a subnet?

[David Wuertele]

I want to discover all the groups currently in use on a subnet.  Is
there a way to do this with a broadcast request?

I know that I could just run nmblookup on every single host on the
subnet, but that would take forever.  I'd like to just make one or
maybe a few calls.  I'd like to limit the number of calls I make to no
more than one plus the number of workgroups that are in use.

Any advice?
Dave