Define a type alias for an Array of indices that point to the array

General Usage
,
2

Can you try on Julia 1.6rc1? I get

julia> isa([CartesianIndex(1,1), CartesianIndex(2,2)], MyType)
false

I also have

julia> [CartesianIndex(1), CartesianIndex(2)] isa (AbstractArray{CartesianIndex{N}, N} where N)
true