At work, our bathrooms have a light and a fan. The switches are together on
the wall, the one for the light is on the right, and the fan's is on the left.
Additionally, the fan's switch is black, and the light's is white. So, the
switch for the light is the one in white on the right.

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People using the switch have three ways to index the memory: the position
(right,left), the color (white,black), or the mnemonic(light-white-right).
Additionally, the switch for the light is closest to the door, which is good
for groping hands trying to find switches. Alltogether, it is surprisingly
well-planned. 

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