link printf
procedure main()
    while writes("Line? ") & line := read() do {
        line ? every m := aNbNcN() do
            printf("At %d: '%s'\n", m[1], m[2])
        }
end

procedure aNbNcN()
    tab(upto('a')) &
    start := &pos &
    as := tab(many('a')) &
    bs := tab(many('b')) &
    cs := tab(many('c')) &
    *as = *bs = *cs &
    suspend [start, as || bs || cs]
end