String-out definition

[masb@arco.NA.CNR.IT (Massimo Bigliardo)]

In the adsp.lsp code there's an example of client/server communication
between two mac's. Unfortunately, the client code contains a call to 
string-out, which turns to be an undefined function, both in the macl 
system and in ACL!
Did anyone encounter the same problem, and solve it?
I tried different ways, such as using force-output, or string-read-immediate,
but none of them worked. Any suggestion welcome.
Massimo