// We see a namespace interface followed
// by definition/implementation of the functions
// in the namespace.

namespace N{          // The namespace interface
  int f(int i);
  double g();
}

int N::f(int i){      // The namespace implementation
  return 2*i;
}

double N::g(){
  return f(2);
}


int main(){
  using N::f; 

  int r = f(5);
  double d = N::g();
}