doc/figs/example-reduce.txt

   1        .------------------.
   2        |     State 1      |
   3        | 3 a: "0" . [";"] |
   4        | 4 b: "0" . ["."] |
   5        `------------------'
   6              /     \
   7             /       \ ["."]
   8            /         \
   9           v           v
  10          / \         / \
  11         / R \       / R \
  12 (green) \ 3 /       \ 4 / (green)
  13          \ /         \ /