Craft a musical piece that abides by the prescribed structural guidelines and the given theme.
X:1
L:1/8
M:2/4
K:D
['e z', 'd z'  
X:1
L:1/8
M:2/4
K:D
|: d z d z | fddd | e z e z | geee | fagf | edcd | e z c z |1 dDFA :|2 d2 z a |: A z a z | 
 A z g z | A z f z | ecAc | d z d z | befg | fdec |1 dafd :|2 dDFA |]  