//Members
private final int MAX_NUMBER = 6, the largest value of a die
private final int MIN_NUMBER = 1, the smallest value of a die
private final int NO_NUMBER, set to any number which is not legal, e.g., 0
private int number, the current value of the die

constructor
PRECONDITION:	none
INPUT:		none
PROCESS:	sets the value of number to be NO_NUMBER
OUTPUT:		none
POSTCONDITION:  number has been initialize

roll
PRECONDITION:	none
INPUT:		none
PROCESS:	chooses a random number from 1 to 6 and assigns it to number
OUTPUT:		none
POSTCONDITION:  number has been modified

getNumber
PRECONDITION:	none (except roll has been called at least once)
INPUT:		none
PROCESS:	returns the value of number
OUTPUT:		int, the value of number
POSTCONDITION:	none