I just want to suggest making the max number of added series configurable.  I see it's hard coded to 10, unlike the max number of series data points. I'm using the CLI as it's the ‘preferred’ method, and I rather not have to start customizing the image.  For local testing, support for more series would be nice to be able to render additional plots.  In my case I use the series plots to render zone lines so that I can better understand what my algorithm is doing.  Uniquely identifying series allows me to stack multiple zone lines on top of each other.  Also, it keeps adjacent zone max/min series of being confused with one another by charting tools.  With the limit it's difficult to do this as 10 series are quickly used up.