Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:4/4
K:C
['d2 c Bcd A2 G FED G2', 'D2 A ded ded efe ecA fgf']  
X:1
L:1/8
M:4/4
K:C
[M:6/8][K:D] a"^Planxty Irwin" .e e!p!ea[Q:1/8=140]"^allegretto".B/c/ | d2 c Bcd | A2 G FED | 
 G2 E FGA | C2 D E2 A | d2 c Bcd | A2 G FED | G2 E FGA | D3 D2 || A | ded ded | efe ecA | fgf efd | 
 c2 B A>Bc | d2 c Bcd | A2 G FED | G2 E FGA | D3 D2 |]  