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          / \           / \
  12         / R \         / R \
  13 (green) \ 3 /         \ 4 / (green)
  14          \ /           \ /
  15           .             .