private void sanityCheck(String seriesName, List<?> xData, List<? extends Number> yData, List<? extends Number> bubbleData) {

    if (seriesMap.keySet().contains(seriesName)) {
      throw new IllegalArgumentException("Series name >" + seriesName + "< has already been used. Use unique names for each series!!!");
    }
    if (yData == null) {
      throw new IllegalArgumentException("Y-Axis data cannot be null!!! >" + seriesName);
    }
    if (yData.size() == 0) {
      throw new IllegalArgumentException("Y-Axis data cannot be empty!!! >" + seriesName);
    }
    if (xData != null && xData.size() == 0) {
      throw new IllegalArgumentException("X-Axis data cannot be empty!!! >" + seriesName);
    }
    if (bubbleData.size() != yData.size()) {
      throw new IllegalArgumentException("Bubble Data and Y-Axis sizes are not the same!!! >" + seriesName);
    }
  }