question: protected double applyOperator ( double first , double second ) { switch ( m_operator ) { case '+' : return ( first + second ) ; case '-' : return ( first - second ) ; case '*' : return ( first * second ) ; case '/' : return ( first / second ) ; case '^' : return Math . pow ( first , second ) ; } return Double . NaN ; }
target:  Apply this operator to the supplied arguments