OpenCV uses HSV for many of it's conversions and comparing and is one of the ideal color ranges to develop in.
You will see yourself trying to convert using various different ways, but with the Rgb2Hsv script, you won't have any issues
Simply enter into your command line python Rgb2Hsv.py 255 0 0
And it will convert your Rgb colors in an instant to the command line.
If you're copying and pasting from another site an Rgb colors feel free to paste it in with the commas and it will handle it accordingly: python Rgb2Hsv.py 125, 200, 50