Hello,
I don't understand the hsvToRgb node's behaviour.
With a such node plugged to the color input of a lambert node, here what happens :
If I click on the color swatch in the HsvToRgb attributes and set in the Color chooser the HSV values to a pure red (360,1,1), the color swatch in the parameters is red, but the Out Rgb parameter is (0,0,0). It should be (from my point of view, according the parameter name) pure red, so (1,0,0).
And the rendering of the lambert swatch in the Hypershade is black, instead of red.
To get red, I have to set the saturation to 0 (???), so the HSV values must be (360,0,1). It's making me crazy.
If you have an idea, it is welcome. 
Thanks !