You execute that on any node in your system and send it a message `{become, fun some_function/0}`. Once it receives that conforming message (a tuple of two items, the atom `become` and a 0-ary function) and that node will stop being a "universal server" and become whatever process "some_function" describes.

And in his case he had access to some 9000 computers. If each was running at least one Erlang node and each node was running a universal server, then with a very simple program he could write a function, serialize the function, and distribute the function to his 9k+ running universal servers and turn them into 9k+ specialized servers.