original
start
b
    start
    c
    d
    e
    end
    f
    start
    g
    h
    i
    end
j
end


 analysis:
    - note that range operator is set to true when $flag1 is true
           becomes false only after $flag3 has been set to true

0, 0, 0, a
0, 0, 0, a
0, 0, 0, a
1, 1, 0, start          success
0, 1, 0, b              success
1, 1, 0,     start      success
0, 1, 0,     c          success
0, 1, 0,     d          success
0, 1, 0,     e          success
0, 1, 0,     end        success
0, 0, 0,     f          success
1, 1, 0,     start      success
0, 1, 0,     g          success
0, 1, 0,     h          success
0, 1, 0,     i          success
0, 1, 0,     end        success
0, 0, 0, j              success
0, 0, 1, end            success
0, 0, 0, k
0, 0, 0, k
0, 0, 0, l