RGB(red, green, blue) or RGB(shortcut)
Generates an RGB true colour value.
red, blue and green represent the intensity of each colour. A value of zero
represents black and 255 represents full intensity.
shortcut allows common colours to be specified by naming them. The colours
that can be named are white, black, blue, green, cyan, red, magenta, yellow,
brown, white, orange, pink, gold, salmon, beige, lightgrey and grey (or USA
spelling gray/lightgray). For example, RGB(red) or RGB(cyan).