class Parent
end

class Child1 < Parent
end

class Child2 < Parent
end

puts [Child2, Child1, 12]

> Error in ./arraytest.cr:10: no overload matches 'Pointer((Int32 | Parent+:Class))#[]=' with types Int32, Child2:Class
> Overloads are:
>  - Pointer((Int32 | Parent+:Class))#[]=(offset, value : (Int32 | Parent+:Class))
>
> puts [Child2, Child1, 12]