Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
M:2/4
K:G
['g_Bc/d/B/A/ G2']  
X:1
L:1/8
M:2/4
K:G
 _B/c/ | d>c_BA | G_B/c/dd | _eec/c/c | d2 z d | d>_e=fd | c_B/c/dc | _B>cdB | AG/A/_Bd | 
 g_Bc/d/B/A/ | G2 d2 | g_Bc/d/B/A/ | G2 z |]  