Hello,

I really like the new iteration protocol, and I’m happy to see it being spread across packages. However, I usually have the problem, that I work with multidimensional arrays that is often not supported directly. In the MWE below, I use `gseidel!`

from IterativeSolvers.jl. The method accepts 1-and 2-d arrays but mine are 2-and 3d arrays, thus I need to copy and slice arrays to fit within a for loop.

Are there more idiomatic ways of doing the same?

```
using IterativeSolvers
n = 10
m = 3
A = rand(n,n,m)
b = rand(n,m)
x1 = zeros(n)
# 2d
@time gauss_seidel!(x1, A[:,:,1], b[:,1]; maxiter=10)
# 3d
x2 = zeros(n,m)
xt = zeros(n)
@time for i = 1:m
xt .= x2[:,i]
gauss_seidel!(xt, A[:,:,i], b[:,i]; maxiter=10)
x2[:,i] .= xt
end
x1 == x2[:,1]
```

Thanks!

EDIT:

Benchmarking gives 3 and 27 allocations, respectively.