Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
M:4/4
K:G
['BG G2 BGAG EAA^G AcBA', 'g2 dg bgag eaab'  
X:1
L:1/8
M:4/4
K:G
 A | BG G2 BGAG | EAA^G AcBA | GFGA Bdef | g2 fa gedc | BG G2 BGAG | EAA^G AcBA | GABd gedB | 
 cedc BG G :| f | g2 dg bgag | eaab agef | gedB GBdB | ecAB cdef | g2 dg bgag | eaab aged | 
 Bdef gedB | cedc BG G :|  