Dictionaries

A Dictionary is a set S mde up of n elements: x0  x1  x2  x3 ... xn-1  that
has the following functions.

Functions:
createEmptySet()	returns a newly created empty priority queue
lookUp(S, k)   		returns the node in S that has the key k 
insert(S, x)		returns S with x added  
delete(S, k)  		returns S with x (found using x.k) removed 
isEmptySet(S)		returns true if S is empty and false if it is not