tokenize = iter (sep, esc: char, s: string) yields (string)
    escape: bool := false
    part: array[char] := array[char]$[]
    for c: char in string$chars(s) do
        if escape then
            escape := false
            array[char]$addh(part,c)
        elseif c=esc then
            escape := true
        elseif c=sep then
            yield(string$ac2s(part))
            part := array[char]$[]
        else
            array[char]$addh(part,c)
        end
    end
    yield(string$ac2s(part))
end tokenize

start_up = proc ()
    po: stream := stream$primary_output()
    testcase: string := "one^|uno||three^^^^|four^^^|^quatro|"

    for part: string in tokenize('|', '^', testcase) do
        stream$putl(po, "\"" || part || "\"")
    end
end start_up