Source: Positive Declarer Play By Terence Reese, Julian Pottage
After your forcing 3
the next three bids were cuebids — more effective than Blackwood when someone has a void. West leads the 
K (king from ace-king against a slam). How will you continue?
FIRST LOOK
There are eleven top tricks and, if trumps break 2-2, you can cash four diamonds and ruff a club in dummy for a twelfth. If not, you might think of an endplay if West holds the top hearts and the 
K. The snag is that if you play off all your winners outside clubs you will finish in the wrong hand. Is there a better line?
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Assuming that the trumps split 3-1 (or 4-0) you will find yourself a trick short. A dummy reversal is an idea but the entry situation is such that you cannot rely on being able to ruff four hearts in your hand and then return to dummy to draw the last trump. Also, somebody might ruff an early round of diamonds. A safe line does exist but you need to see it at once. Take your finger off the trump and discard a club instead. Say that West exits with a diamond. You can win in dummy, ruff a heart, and lead the K.
When all follow you can play two more rounds and ruff another heart. Then you run the diamonds and table your last trump. West, at the finish, will be obliged to discard from A K J in front of dummy’s Q Ax.
Note that ruffing the first heart and exiting with the queen later does not work. If you try it, West will leave his partner in control of the suit. It is equally ineffective to ruff the first heart and try to duck one later: East will win and return a club to take out dummy’s entry in the suit, thereby destroying the squeeze.