Tutorial 04: `predict(..., rows = 1:3)`

[roland-KA]

In part 04 of the tutorial, in section 'The tuning wrapper' there is a predict statement applied to the tuned model/machine: predict(tuned_mach, rows = 1:3)

To me it is not quite clear why the parameter 1:3 is given to rows. I would have expected that XHorse (or a subset of it) would be used.