possibles

# File actionpack/lib/action_dispatch/journey/formatter.rb, line 121
        def possibles(cache, options, depth = 0)
          cache.fetch(:___routes) { [] } + options.find_all { |pair|
            cache.key?(pair)
          }.map { |pair|
            possibles(cache[pair], options, depth + 1)
          }.flatten(1)
        end