m/doctest/issues/121).

## ```operator<<``` overload for ```std::ostream```

This is the standard way of providing string conversions in C++ - and the chances are you may already provide this for your own purposes. If you're not familiar with this idiom it involves writing a free function of the form:

```
std::ostream& operator<< (std::ostream& os, const T& value) {
    os << convertMyTypeToString(value);
    return os;
}
```

(where ```T``` is your type and ```convertMyTypeToString``` is where you'll writ