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       # MATH show some simple function calls
       # and show a way to remember functions across statements
[hear] (= 49 /
         (? square / square 7) (? x / * (x) (x)));

[hear] (= 49 /
         (? square / square 7) (? x / * (x) (x)));

[hear] (= 81 /
         (? square / square 9) (? x / * (x) (x)));

[hear] (= 16 /
         (? square / square 4) (? x / * (x) (x)));

[hear] (= 81 /
         (? square / square 9) (? x / * (x) (x)));

[hear] (= 9 /
         (? square / square 3) (? x / * (x) (x)));

[hear] (= 1 /
         (? square / square 1) (? x / * (x) (x)));

[hear] (= 1 /
         (? square / square 1) (? x / * (x) (x)));

[hear] (define square / ? x / * (x) (x));

[hear] (= (square 9) 81);

[hear] (= (square 2) 4);

[hear] (= (square 8) 64);

[hear] (= (square 1) 1);

[hear] (define plusone / ? x / + (x) 1);

[hear] (= (plusone 3) 4);

[hear] (= (plusone 6) 7);

[hear] (= (plusone 3) 4);

[hear] (= (plusone 0) 1);