(lightness-from-rgb 
.(turbulate 
..(checker 
...(checker 
....(max-component 
.....(vcos 
......(sigmoid 
.......(rgb-from-hsl [1.7458 2.7844])))) 
....(x 
.....(vsin 
......(hsl-from-rgb pos)))) 
...(sigmoid [-1.9149 0.0241 1.911 -2.7049])) 
..(checker 
...(theta 
....(height 
.....(gradient 
......(rgb-from-hsl 
.......(vdivide 
........(vround [-2.649 -1.121 -0.8449 1.8884]) 
........(y [0.0815 -1.0507 0.8295])))))) grain)))