index++
			if !required && (index < startIdx || index > endIdx) {
				// not in the range. Skip!
				return
			}
			WalkStackFrames(allFrames, v.Stack, func(id int) {
				s := strconv.Itoa(id)
				requiredFrames[s] = allFrames[s]
			})
			WalkStackFrames(allFrames, v.EndStack, func(id int) {
				s := strconv.Itoa(id)
				requiredFrames[s] = allFrames[s]
			})
			if written == 0 {