Utilizing the provided musical theme and letter-based structure, compose a piece of music.
X:1
L:1/8
M:4/4
K:Amin
['AGAB cAAa AAgA']  
X:1
L:1/8
M:4/4
K:Amin
|:"Am" AGAB cAAa | AAgA AfAA |"F" cBcd eAAc |"G" Bcdc BcBG |"Am" AGAB cAAa | AAgA Afec | 
"G" BGGB"F" cedB |"Em" cBGB"Am" ABce ::"C" gccg ceec |"F" AccA FAAF |"D" cAAc eedc | 
"G" dGGB"E" dcBc |"Am" AGAB cAAa | AAgA AfAA |"G" BGGB dedB |"Em" ed"G"BG"Am" A4 :|  