if it.node.Left != nil { // Left Child
            dotString += (strconv.Itoa(it.node.nodeIndex) + " -> " + strconv.Itoa(it.node.Left.nodeIndex) + ";")
        } else {
            dotString += (strconv.Itoa(it.node.nodeIndex) + " -> " + strconv.Itoa(NilNodes) + ";")
            NilNodes++