(checker 
.(adjust-hue 
..(radius 
...(sigmoid 
....(vabs [-1.131 -1.0549 0.888]))) 
..(sigmoid 
...(vpow 
....(red-from-hsl 
.....(polar 
......(height-normal 
.......(z 
........(saturation-from-rgb -2.3924))))) 
....(sigmoid 
.....(t pos))))) 
.(vpow 
..(vdivide [-1.1268 0.9934 -2.2069 -1.2945] 
...(adjust-hue 
....(vfloor 
.....(alpha 
......(t -2.0733))) 
....(rotate 
.....(blue-from-hsl 
......(height-normal pos)) 
.....(red-from-hsl 
......(min-component 
.......(vabs grain)))))) 
..(lightness-from-rgb [-1.6525 -2.292 2.6057])))