Develop a musical piece that combines the given theme and letter-structured outline.
X:1
L:1/8
Q:1/2=80
M:4/4
K:Bb
['G2 B2 A2 G2', 'G6 B4 d2 cB defd B4 F4']  
X:1
L:1/8
Q:1/2=80
M:4/4
K:Bb
 G2 B2 A2 G2 | d4 B4 | F2 c2 A2 F2 | cBA>G ^F3 E/F/ | G2 B2 A2 G2 | d3 c/d/ e3 d | c2 Bc A2 d2 | 
 B2 G6 :: B4 d2 cB | defd B4 | F4 A2 GF | cBA>G ^F3 E/F/ | G2 A>B cd e2 | d2 f2 =efge | 
 b2 ag a2 ^f2 | g4- g4 :|  