The book argues that the violin was associated with Jewishness (fiddler on the roof etc.), the forest meeting around the boy's grave at the end is reminiscent of the way that many Soviet Jews met up in forests to avoid having the meeting noted down by the KGB, something something the animation style.... unfortunately I've already turned the book in so I can't check back to see.

It wasn't reaching nearly as far as Dark Crocodile Gena was reaching, but I did definitely feel these were signs that would only be legible to someone who was already looking for signs that the Pioneer was Jewish.