Priority Queues

A Priority Queue Set S = x0  x1  x2  x3 ... xn-1     n =  # elements
A priority queue is like a list but the nodes are only accessed in
some specific order.

Functions:
createEmptySet()	returns a newly created empty priority queue
findMin(S)   		returns the minimum node with respect to ordering 
deleteMin(S)  		returns S with the minimum node removed 
insert(S, x)		returns S with x added  
isEmptySet(S)		returns true if S is empty and false if it is not