about functions question

[NoName]

I try it:

def b():
  ...
  a()
  ...

def a():
  ...
  b()
  ...

b()
it's not work.

Is it possible pre-define function like in c++ or place functions code
after main block?

int a();
int b();

int main ()
{
...
a();
...
}

int a()
{
...
b();
...
}

int b()
{
...
a();
...
}

=) sorry for my eng;)