Where did the output 16 come from?

Question

def fun1(func, arg):
return func(func(arg))
def fun2(x):
return x*x
print(fun1(fun2, 2))

Answer 1

That code won't run for me as is, but if the 2nd line of fun1 was instead like this:
def fun1(func, arg):
return func(func(arg))
then 16 is because
fun1(fun2, 2)
fun2(fun2(2))
fun2(4)
16

Answer 2

calling fun1(fun2,2) returns fun2(fun2(2)) which evaluates as follows:
fun2(2*2) as fun2(x)=x*x
fun2(4)
finally 4*4
hence 16

Answer 3

2×2=4
4×4=16

Answer 4

yeah the code is like what u type potto.. sorry my bad