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

?- declare(x, 3).
true.

?- declare(y, 7).
true.

?- display_bindings.
x: 3
y: 7
true.

?- add(x, y, add_ans).
true.

?- display_bindings.
x: 3
y: 7
add_ans: 10
true.

?- sub(add_ans, y, sub_ans).
true.

?- display_bindings.
x: 3
y: 7
add_ans: 10
sub_ans: 3
true.

?- mul(x, y, mul_ans).
true.

?- display_bindings.
x: 3
y: 7
add_ans: 10
sub_ans: 3
mul_ans: 21
true.

?- div(mul_ans, y, div_ans).
true.

?- display_bindings.
x: 3
y: 7
add_ans: 10
sub_ans: 3
mul_ans: 21
div_ans: 3
true.

?- declare(a, 2).
true.

?- declare(b, 2).
true.

?- display_bindings.
x: 3
y: 7
add_ans: 10
sub_ans: 3
mul_ans: 21
div_ans: 3
a: 2
b: 2
true.

?- declare(e, 2).
true.

?- declare(f, 2).
true.

?- exp(e, f, exp_ans).
true.

?- display_bindings.
x: 3
y: 7
add_ans: 10
sub_ans: 3
mul_ans: 21
div_ans: 3
a: 2
b: 2
e: 2
f: 2
exp_ans: 4
true.