Simplify state in SubBlockIterator

src/blockbroadcast.jl

@@ -49,7 +49,7 @@ similar(bc::Broadcasted{PseudoBlockStyle{N}}, ::Type{T}) where {T,N} =
     SubBlockIterator(subblock_lasts::Vector{Int}, block_lasts::Vector{Int})
     SubBlockIterator(A::AbstractArray, bs::NTuple{N,AbstractUnitRange{Int}} where N, dim::Integer)
 
-An iterator for iterating `BlockIndexRange` of the blocks specified by
+Return an iterator over the `BlockIndexRange`s of the blocks specified by
 `subblock_lasts`.  The `Block` index part of `BlockIndexRange` is
 determined by `subblock_lasts`.  That is to say, the `Block` index first
 specifies one of the block represented by `subblock_lasts` and then the
@@ -85,7 +85,7 @@ view(A, idx) = 2:3
 view(A, idx) = 4:4
 view(A, idx) = 5:6
 
-julia> [idx.block.n[1] for idx in SubBlockIterator(subblock_lasts, block_lasts)]
+julia> [Int(idx.block) for idx in SubBlockIterator(subblock_lasts, block_lasts)]
 4-element Vector{Int64}:
  1
  2
@@ -114,12 +114,8 @@ Base.length(it::SubBlockIterator) = length(it.block_lasts)
 SubBlockIterator(arr::AbstractArray, bs::NTuple{N,AbstractUnitRange{Int}}, dim::Integer) where N =
     SubBlockIterator(blocklasts(axes(arr, dim)), blocklasts(bs[dim]))
 
-function Base.iterate(it::SubBlockIterator, state=nothing)
-    if state === nothing
-        i,j = 1,1
-    else
-        i, j = state
-    end
+function Base.iterate(it::SubBlockIterator, state=(1,1))
+    i, j = state
     length(it.block_lasts)+1 == i && return nothing
     idx = i == 1 ? (1:it.block_lasts[i]) : (it.block_lasts[i-1]+1:it.block_lasts[i])