Make a python class that uses a list to create a set of numbers.  Sets have no duplicates and no ordering.  
It should work for a main shown below.  You will need (maybe) a constructor and methods

	void insert(int)
	string toString(void)
	NumSet minus(NumSet)
	NumSet __iter__(void)
	int next(void)

There is one point of optional extra credit for people who get "+" and "-" to work doing set union and set difference.


primes = NumSet()
primes.insert(2)
primes.insert(3)
primes.insert(5)
primes.insert(5)
primes.insert(3)
primes.insert(2)
primes.insert(7)
primes.insert(11)

print "The should print 2,3,5,7 and 11 in any order.  No duplicates"
print primes.toString()


evens = NumSet()
for i in range(2,10,2)
	evens.insert(i)
evens.insert(2)
evens.insert(4)
print "The should print 2,4,6, and 8 in any order.  No duplicates"
print evens.toString()


oddprimes = primes.minus(evens)
print "Should print 3,5, 7, and 11 in any order"
print oddprimes.toString()

print "Should print 2,3,5,7 and 11 in any order"
for i in primes
	print i

x = primes.max()
print "Should print 11"
print x