The captain of a ship looked into the dark night and saw lights in the distance. Immediately he told his signalman to send a message: "Alter your course 10 degrees south."
Promptly a return message was received: "Alter your course 10 degrees north."
The captain was angered his command had been ignored. So he sent a second message: "Alter your course 10 degrees south - I am a captain."
Soon another message was received: "Alter your course 10 degrees north. I am seaman third class Jones."
Immediately the captain sent a third message, knowing the fear it would evoke: "Alter your course 10 degrees south - I am a battleship."
Then the reply came: "Alter your course 10 degrees north - I am a lighthouse."
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