Compose a piece of music that follows both the given musical theme and the letter-based structure provided.
X:1
L:1/8
M:6/8
K:F
['c f2 f fca g2 g gcb', 'g2 g', 'c2 c']  
X:1
L:1/8
M:6/8
K:F
 c | f2 f fca | g2 g gcb | agf cfe | f2 f f2 :: g | a2 a afd | g2 g gec | a2 a afd | g2 g gec | 
 f2 f fca | g2 g gcb | agf cfe | f2 f f2 :: d | c2 c cfd | c2 c cfd | c2 f gab | agf efd | 
 c2 c cfd | c2 c cfe | cba gfe | fcA F2 :|  