Punch paper coded rolls were interchangeable and thus provided a greater variety of music than, say, a music box which operated on a similar principle; however the player piano could also be played by a live performer. This allowed for greater variety still, and when the pianist was a young child, the results could be a startling and dramatic cacophony.
What a wonderful plaything for the nascent musician, who learned that the keys could be played not only with the fingers for which they were designed, but with teddy bears, toy vehicles, fore-arms, elbows, noses and fore-heads.