Dygraphs-->Hairlines question

[Shashikant]

Hello,

This is regarding https://github.com/danvk/dygraphs/blob/master/tests/hairlines.html

I have a question, I want to draw maximum 2 hairlines on graph. How can I restrict user to draw just 2 lines.

Is it supported in the API? Where can I get the details?
If not supported then how can I do that? Any idea.

Thanks and regards.