digraph sii {
    node [fontname="Helvetica"]
    edge [fontname="Helvetica", fontsize="12"]

    start_reading
    start_reading -> read_check [weight=5]

    read_check
    read_check -> error
    read_check -> read_fetch [weight=5]

    read_fetch
    read_fetch -> error
    read_fetch -> end [weight=5]
    read_fetch -> read_fetch

    start_writing
    start_writing -> write_check [weight=5]

    write_check
    write_check -> error
    write_check -> write_check2 [weight=5]

    write_check2
    write_check2 -> error
    write_check2 -> end [weight=5]
    write_check2 -> write_check2

    end

    error
}