[segmondy]

Not practical, there are infinitely many functions that could produce such result

here is such psuedo code foo(x) { if (x <= 5) { x * 2 } else { x } } foo1(x) { if (x <= 6) { x * 2 } else { x+1 } } foo1(x) { if (x <= 7) { x * 2 } else { x+2 } }