Oh goodness, I hadn't tested my summary example without GSL. If you
haven't yet installed GSL I wouldn't recommend trying that particular
example. With GSL it takes under a second to summarize the forward.
Without GSL it takes many minutes.

Instead try giving it a dozen or so sentences. You can limit how many
sentences end up in the summary with an optional parameter like this:

x = "This text deals with dogs. Dogs. This text involves dogs too.
Dogs! This text revolves around cats. Cats. This text also involves
cats. Cats! This text involves birds. Birds."

x.summary 2

Outputs:

"This text involves dogs too [...] This text also involves cats"