Music in each key

[ 0] Music under the no-sharp-or-flat-keys signature
[ 1] Music under the one-sharp-key signature
[ 2] Music under the two-sharp-keys signature
[ 3] Music under the three-sharp-keys signature
[ 4] Music under the four-sharp-keys signature
[ 5] Music under the five-sharp-keys signature
[ 6] Music under the six-sharp-keys signature
[ 7] Music under the five-flat-keys signature
[ 8] Music under the four-flat-keys signature
[ 9] Music under the three-flat-keys signature
[10] Music under the two-flat-keys signature
[11] Music under the one-flat-key signature