Players do not choose their own disease. Instead, choose one disease
randomly, for all the players.
+### Nervousness
+
+In the final round, when drawing is supposed to be secret and
+simultaneous:
+
+Each player with Nervousness chips puts some rubies in their bag.
+When drawing a chip, they may (by feel) choose to draw a ruby instead.
+When the ruby is revealed, it means they are placing one of their
+Nervousness chips.
+
+A player who drew a ruby selects *which* of their Nervousness chips
+they are playing before anyone makes other decisions about how to play
+their chips. If more than one player has more than one Nervousness
+chip to choose from, the applicable players each choose a Nervousness
+chip in turn order.
+
Blacks book V
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