@rohit_ you need to first (use 'overtone.live)
or (use 'overtone.core)
, either that, or there was an error evaluating overtone.samples.piano, it's using freesoundAPI, I'm not sure how well it has aged. (I used the sampled piano in a live-coding set 2 years back without problems)
I did exactly that and it took an hour to download the free sound samples so I'm not sure why
I'll post the code here