keys_to_symbols

# File actionpack/lib/action_controller/vendor/html-scanner/html/node.rb, line 44
      def keys_to_symbols(hash)
        Hash[hash.keys.map do |k|
          raise "illegal key #{k.inspect}" unless k.respond_to?(:to_sym)
          [k.to_sym, hash[k]]
        end]
      end