Set Type

A Set is a collection of unique values. If you add a value to a Set that already contains that value, the Set will not change.
dim <VARIABLE> as Set of <TYPE>
If you have values of type Number, then a set of unique numbers would be Set of Number.
dim x as Map of Number
x = x + 999
x = x + 999 ' already added; this has no effect
print Contains(x, 999) ' prints true