Consider the ComplexNumber class shown partially below. This specification (and the partial implementation) contains four errors. Identify the errors by correcting them. class ComplexNumber { ComplexNumber () :: r = 0.0 { i = 0.0; } ComplexNumber (double real, double imaginary); friend ComplexNumber operator+ (const ComplexNumber&); friend ostream& operator<<(const ostream&, const ComplexNumber&); // other member function prototypes private: double r; double i; };