Write a Java enumeration LetterGrade that represents letter grades A through F, including plus and minus grades. You can use the Suit enumeration code as an example. Define a private instance variable to hold a boolean value that is true if the grade is passing. Also, define a constructor that initializes this instance variable, an accessor method called isPassing() that returns its value, and a method toString() that returns the grade as a String. Finally, write a program to demonstrate / test the enumeration.

/** An enumeration of card suits. */ enum Suit { CLUBS("black"), DIAMONDS("red"), HEARTS("red"), SPADES("black"); private final String color; private Suit(String suitColor) { color = suitColor; } public String getColor() { return color; } }