isempty fails for AFArray

[WKusnezow]

julia> isempty([1.f0,2.f0])
false

julia> isempty(AFArray([1.f0,2.f0]))
ERROR: MethodError: no method matching iterate(::AFArray{Float32,1})
Closest candidates are:
  iterate(::Core.SimpleVector) at essentials.jl:589
  iterate(::Core.SimpleVector, ::Any) at essentials.jl:589
  iterate(::ExponentialBackOff) at error.jl:171
  ...
Stacktrace:
 [1] isempty(::AFArray{Float32,1}) at ./essentials.jl:721
 [2] top-level scope at none:0