Here it is in Julia:

     julia> join([1 2 3], ", ")
     "1, 2, 3"


     julia> split("1, 2, 3", ", ")
     3-element Vector{SubString{String}}:
      "1"
      "2"
      "3"

Note how they are both functions. The data that they operate on is the first argument, in both cases. The optional second argument is the obvious next most important thing, the delimiter. Other optional arguments come after that. There is nothing to remember, because it makes sense.