Why sum of empty set is not zero ?

```
julia> eltype(dane)
Any
julia> sum(dane[:,9])
6.54132454e8
julia> dane[(mies20) .& (dane[:,7].==dealerzy[1]),9]
1-element Array{Any,1}:
2032.0
julia> dane[(mies20) .& (dane[:,7].==dealerzy[2]),9]
Any[]
julia> sum(dane[(mies20) .& (dane[:,7].==dealerzy[2]),9])
ERROR: MethodError: no method matching zero(::Type{Any})
Closest candidates are:
zero(::Type{Union{Missing, T}}) where T at missing.jl:104
zero(::Type{Measures.Length{:mm,Float64}}) at C:\Users\PC\.julia\packa
zero(::Type{Measures.Length{:pct,Float64}}) at C:\Users\PC\.julia\pack
...
julia> isreal(dane[(mies20) .& (dane[:,7].==dealerzy[2]),9])
true
```

Paul