hello
fun()=7 should be equal 7
square(2)=4 should be equal 4
f3(1,2,3)=9 should be equal 9
f4(1,2,3)=4 should be equal 4
a=1 should be 0 or >1<
a=2 should be 0 or >2<
a=3 should be 0 or >3<
a=4 should be 0 or >4<
fb()=1 should be 1
fb()=2 should be 2
fb()=3 should be 3
fc()=1 should be 4 or >1<