Thank you very much Mauro, that was the mistake ! :)
> Array{String}(0)
>
> works. The other creates a zero-dimensional vector (just like a scalar)
> to which you cannot push.
>
> > julia> a = Array{String}()
> > WARNING: Base.String is deprecated, use AbstractString instead.
> > likely near no file:0
> > 0-dimensional Array{AbstractString,0}:
> > #undef
> >
> >
> > julia> for k in keys(dict)
> > if dict[k] < 2
> > continue
> > end
> > push!(a, k)
> > end
> > ERROR: MethodError: `push!` has no method matching
> push!(::Array{AbstractString
> > ,0}, ::ASCIIString)
> > Closest candidates are:
> > push!(::Any, ::Any, ::Any)
> > push!(::Any, ::Any, ::Any, ::Any...)
> > push!(::Array{Any,1}, ::ANY)
> > ...
> > [inlined code] from none:5
> > in anonymous at no file:0
>
