conj is a pun

[oxinabox]

conj(s::PersistentSet{T}, val) should not overload Base.conj.
Base.conj is complex conjugation.

I suggest replacing it with push.
We already provide push as an alias for conj.

push is a good name since push!(::Set, val) is how you add one element to a Base.Set

[shashi]

I agree