The Volume indicator looks for abnormality in the volume. Looking for abnormal volume spike could be an indication of an Alpha Volume, but it is not possible to identify which spike is abnormal from a given look back period. The code calculates this for you. And the result is displayed nicely as a different colour. It could also be displayed as a histogram.
Please notice the left hand side small volume spikes with Alpha Candles. They are the indication of explosive moves. Supporting Volume and Price action.
Below is the histogram view of the same chart
