?- consult('proglanghw2.pro').
true.

?- pieces.
chopin
chopin
chopin
chopin
chopin
liszt
liszt
false.

?- note.
a
b
c
d
e
f
g
true.

?- quarter(Pitch).
a
d
false.

?- whole(Pitch).
b
e
false.

?- half(Pitch).
c
f
g
false.

?- beats(half, A).
A = 2 ;
A = 2 ;
A = 2.

?- beats(whole, A).
A = 4 ;
A = 4 ;
false.

?- beats(quarter, A).
A = 1 ;
A = 1 ;
false.

?- composers.
chopin
chopin
chopin
chopin
chopin
liszt
liszt
true.

?- beats_of_pitch(a, A).
A = 1 ;
false.

?- halt.