Write a stub for the following function prototype:

```
double root( double a, double b, double c, int i);
// Precondition: a != 0 and a, b, c are coefficients of
// a quadratic equation a*x*x + b*x + c = 0 The value
// of i is either +1 or -1 to choose which root.
// Postcondition: return value, x, satisfies the
// equation a*x*x + b*x + c = 0
```

```
#include
// stub functions example
double root(double a, double b, double c, int i)
{
using namespace std;
cout << "executing function\n"
<< "double root(double, double, double)"
<< endl;
return 2.0;
```