Performs a "minus" of set anotherSet from set setOne.
A set containing
setOne - anotherSet elements. a null reference
(Nothing in Visual Basic) if setOne is a null reference
(Nothing in Visual Basic).
This returns a set of all the elements in set setOne, removing the elements that are also in set anotherSet. The original sets are not modified during this operation. The result set is a clone of set setOne containing the elements from the operation.