Iterating Operators

Operators that work with iterator objects

These operators allow objects of user-defined types to be used as iterators 
and step values in KeyPgFornextFor...Next statements.

KeyPgOpForOperator For
	Allows an iterator a chance to prepare for the loop.
KeyPgOpStepOperator Step
	Increments an iterator object.
KeyPgOpNextOperator Next
	Determines if the loop should terminate or continue iterating.

