[julia-users] Why does the subtypes method produce an array rather than a set?

[Ray Toal]

I noticed that 

*julia> **subtypes(Type)*

*3-element Array{Any,1}:*

* DataType      *

* TypeConstructor*

* Union *

and was wondering if there was any significance in the order of the 
subtypes. If not, could the method have produced a Set instead?