Hi all! I have a question defining a parametric type which I defined, subtype of AbstractArray:

```
struct CoreM{N} <: AbstractArray{Float64,N}
core::Array{Float64,N}
end
```

I would like to define a CoreM type, which is subtype of AbstractArray{T,3} for fixed N=3 but for type any type `T<:Number`

, something like:

```
struct CoreM2{T} <: AbstractArray{T,3} where T<:Number
core::Array{T,3}
end
```

which however gives me error: `ERROR: invalid subtyping in definition of CoreM2`

Can this be accomplished?