Generate a piece of music.  
X:1
T:Music21 Fragment
C:Music21
L:1/4
M:none
I:linebreak $
K:none
V:1 treble 
V:1
 C C{/F} E F | G2 B B | c c B B | G4 ||{/G} E F{/A} G F | E2 C2 | B,2 G, B, | C C C2 || %8
{/B,} C2{/F} E2 | F E2 F | G G E2 | F E C2 || %12  