How to dispatch on an iterable (e.g. accept both tuple or array)

General Usage
3

The SimpleTraits.jl solution fails because numbers are iterable:

using SimpleTraits
using SimpleTraits.BaseTraits

@traitfn f(x::T) where {T; IsIterator{T}} = "iterable"
@traitfn f(x::T) where {T; !IsIterator{T}} = "not iterable"

I get

julia> f((1,2))
"iterable"

julia> f([1,2])
"iterable"

julia> struct A
       end

julia> f(A)
"not iterable"

which looks great, but then

julia> f(1.0)
"iterable"