It is only the introduction of the music. Originally made for bass, but it also works in the guitar. 
 
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G |         2 1 |       2 1   |         2 1 |       2 1   |                                       | 
D |   2   4     |   4       2 |   2   4     |   4       2 |   4   |2|<-Hold until the sound stops | 
A | 4   4       | 4   4       | 4   4       | 4   4       | 4   4                                 | 
E |             |             |             |             |                                       | 
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