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Willie Nelson is a Music Icon.  Not A Country Music Icon, a Music Icon.

And of course, he's one of the most legendary songwriters of the 20th and 21st centuries.

Well, how's this for a week of writing...on a trip to Nashville, Willie wrote 'Crazy, ' 'Funny How Time Slips Away' and 'Nightlife'.  In one week!

Here, Willie tells David Letterman about that week...and how he met Patsy Cline.