# File lib/journey/nfa/transition_table.rb, line 118
      def eclosure t
        stack = Array(t)
        seen  = {}
        children = []

        until stack.empty?
          s = stack.pop
          next if seen[s]

          seen[s] = true
          children << s

          stack.concat inverted[s][nil]
        end

        children.uniq
      end