Mergewith(dicts...)

General Usage
5

maybe, but we probably have 1000:
“this works because our functions are general enough but users probably don’t want this behavior”

this particular case is just because

function mergewith!(combine, d::AbstractDict, others::AbstractDict...)
    foldl(mergewith!(combine), others; init = d)
end

we just returned init=d I guess

and the fact that this is un-typed

mergewith!(combine) = (args...) -> mergewith!(combine, args...)

maybe type this with:

julia> Base.Callable
Union{Function, Type}

?