rep_strings = iter (s: string) yields (string)
    for len: int in int$from_to_by(string$size(s)/2, 1, -1) do
        repstr: string := string$substr(s, 1, len)
        attempt: string := ""
        while string$size(attempt) < string$size(s) do
            attempt := attempt || repstr
        end
        if s = string$substr(attempt, 1, string$size(s)) then
            yield(repstr)
        end
    end
end rep_strings

start_up = proc ()
    as = array[string]
    po: stream := stream$primary_output()
    tests: as := as$["1001110011","1110111011","0010010010","1010101010",
                     "1111111111","0100101101","0100100","101","11","00",
                     "1"]

    for test: string in as$elements(tests) do
        stream$puts(po, test || ": ")
        for rep_str: string in rep_strings(test) do
            stream$puts(po, "<" || rep_str || "> ")
        end
        stream$putc(po, '\n')
    end
end start_up