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[ITS] A display hack originally due to Bill Gosper. Many convergent lines are drawn on a colour monitor in AOS mode (so that every pixel struck has its colour incremented). The lines all have one endpoint in the middle of the screen; the other endpoints are spaced one pixel apart around the perimeter of a large square. The colour map is then repeatedly rotated. This results in a striking, rainbow-hued, shimmering four-leaf clover. Gosper joked about keeping it hidden from the FDA (the US's Food and Drug Administration) lest its hallucinogenic properties cause it to be banned.