code: func copyDeltas(d Deltas) Deltas {
  	d2 := make(Deltas, len(d))
  	copy(d2, d)
  	return d2
  }
docs: // copyDeltas returns a shallow copy of d; that is, it copies the slice but not
  // the objects in the slice. This allows Get/List to return an object that we
  // know won't be clobbered by a subsequent modifications.