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       # MATH show mechanisms for branching
[hear] (intro if);

[hear] (= (if (false) 5 0) 0);

[hear] (= (if (true) 3 0) 3);

[hear] (= (if (false) 6 6) 6);

[hear] (= (if (true) 7 9) 7);

[hear] (= (if (false) 6 6) 6);

[hear] (= (if (true) 2 7) 2);

[hear] (= (if (true) 0 6) 0);

[hear] (= (if (true) 6 9) 6);

[hear] (= (if (true) 0 4) 0);

[hear] (= (if (false) 9 8) 8);

[hear] (= (if (true) 4 6) 4);

[hear] (= (if (false) 1 3) 3);

[hear] (= (if (true) 7 3) 7);

[hear] (= (if (false) 4 9) 9);

[hear] (= (if (false) 2 1) 1);

[hear] (= (if (true) 1 0) 1);