@FunctionalInterface
interface Assign {
    double assess(int id, double percentage);   
}

@FunctionalInterface
interface Assign {
    double assess(int id, double percentage);
    default double computeGrade(double cost) {
                //implementation of computeGrade
    }}

@FunctionalInterface
interface Assign {
    double assess(int id, double percentage);
    default double computeGrade(double cost) {
        //implementation of computeGrade
        } 
    static void display() {
        //implementation of display
    }   
}

@FunctionalInterface
interface Assign {
    double assess(int id, double percentage);
    default double computeGrade(double cost) {
        //implementation of computeGrade
    } 
    static void display() {
        //implementation of display
    }
    public String toString()
    {
        //Implementation of toString() method
    }
}