# File lib/journey/route.rb, line 54
    def score constraints
      required_keys = path.required_names
      supplied_keys = constraints.map { |k,v| v && k.to_s }.compact

      return -1 unless (required_keys - supplied_keys).empty?

      score = (supplied_keys & path.names).length
      score + (required_defaults.length * 2)
    end