[LISP] completion of partial buffer name

[Cliff Heller]

I'm trying to use elisp to write a function that will switch to a buffer
of a certain type.

But I only have the beginning of the name availalble.

say for example: output1, output2, output3
but only one such buffer would exist at any time.

How can I do a non interactive completion on substring "output" to get
the full buffer name and switch to it? 

Thanks.

-- 
"Letters may be used to construct words, phrases and sentences that may be
deemed offensive."
                  -Warning label on children's alphabet blocks