Taskwarrior

for task theming, the tool colortest is perfect.
try this;
get colortest (from.. ) and run;

$ task colors

and then immediately run

colortest -w -r

you will see that the output directly maps to the "task colors" color cube, and shows it as colored text and with the correct rgb code.
As an extra added super-free bonus, mouse over your terminal, selecting all of the colortest output, and now you can see how the colors of the cube look as text-on-color.
If, perchance, this code is very small and compatible, perhaps it could be included ? or at very least, this theme candy should be mentioned in the docs.