How to draw a rainbow-colored line?
 

I have been puzzling over this for several hours... I want to draw either a line or an arc that is multicolored along it's length - a rainbow-colored "stroke" would be ideal I can do overlapping solids with a blend fill and get a line or arc or circle that is multicolored (but not rainbow-colored)... Is there a better way?

I'm stumped! I would appreciate any solution. I appreciate the time of anyone who replies.

Thanks - Brian