to_dot

# File actionpack/lib/action_dispatch/journey/nfa/dot.rb, line 7
        def to_dot
          edges = transitions.map { |from, sym, to|
            "  #{from} -> #{to} [label=\"#{sym || 'ε'}\"];"
          }

          # memo_nodes = memos.values.flatten.map { |n|
          #   label = n
          #   if Journey::Route === n
          #     label = "#{n.verb.source} #{n.path.spec}"
          #   end
          #   "  #{n.object_id} [label=\"#{label}\", shape=box];"
          # }
          # memo_edges = memos.flat_map { |k, memos|
          #   (memos || []).map { |v| "  #{k} -> #{v.object_id};" }
          # }.uniq

          digraph nfa {  rankdir=LR;  node [shape = doublecircle];  #{accepting_states.join ' '};  node [shape = circle];#{edges.join "\n"}}
        end