Hi,

I recently started working with Julia and I ran into an error that I do not understand.

I have a vector of sets of which one set contains one element. I now have candidate elements that I would like to add to the empty sets in the vector but only those elements that are not contained in any other sets should be added.

```
setlist = [Set() for _ = 1:3]
setlist[1] = Set('a')
potential_add = Set(['a', 'b'])
## This does not work
setlist[[2, 3]] .= setdiff!(potential_add, setlist...)
## For one position it works
setlist[2] = setdiff!(potential_add, setlist...)
## This produces the desired result
union!.(setlist[[2, 3]], setdiff!(potential_add, setlist...))
```

Trying to assign the value to multiple positions at once yields the following error

```
ERROR: LoadError: MethodError: Cannot `convert` an object of type Char to an object of type Set{Any}
Closest candidates are:
convert(::Type{T}, ::T) where T<:AbstractSet at set.jl:422
convert(::Type{T}, ::AbstractSet) where T<:AbstractSet at set.jl:423
convert(::Type{T}, ::T) where T at essentials.jl:205
...
Stacktrace:
[1] setindex!(A::Vector{Set{Any}}, x::Char, i1::Int64)
@ Base .\array.jl:839
[2] setindex!
@ .\subarray.jl:317 [inlined]
[3] macro expansion
@ .\broadcast.jl:984 [inlined]
[4] macro expansion
@ .\simdloop.jl:77 [inlined]
[5] copyto!
@ .\broadcast.jl:983 [inlined]
[6] copyto!
@ .\broadcast.jl:936 [inlined]
[7] materialize!
@ .\broadcast.jl:894 [inlined]
[8] materialize!(dest::SubArray{Set{Any}, 1, Vector{Set{Any}}, Tuple{Vector{Int64}}, false}, bc::Base.Broadcast.Broadcasted{Base.Broadcast.DefaultArrayStyle{1}, Nothing, typeof(identity), Tuple{Vector{Char}}})
@ Base.Broadcast .\broadcast.jl:891
[9] top-level scope
```

Desired result

```
3-element Vector{Set{Any}}:
Set(['a'])
Set(['b'])
Set(['b'])
```

Why is it not possible to assign the set to multiple positions in the vector? Thank you for your thoughts!