No need to reach for unicode in this particular case:
julia> "NC_011566" in b
true
As with all operators, though, you can also just call it as a normal function:
julia> in("NC_011566", b)
true
Unlike R, there’s not a general mechanism for putting an arbitrary function in infix position, and this is the only “word” that works like this. All other infix operations are symbols of some sort — which you can define and use yourself.
Ah, thanks. I knew as I was writing that sentence that I was likely to be wrong. If I were feeling snarky I’d say that “isa” isn’t a (dictionary) word!