    # File lib/chef/node/attribute.rb, line 418
          def method_missing(symbol, *args)
            if args.empty?
              if key?(symbol)
                self[symbol]
              elsif key?(symbol.to_s)
                self[symbol.to_s]
              elsif auto_vivifiy_on_read?
                self[symbol] = Mash.new
                self[symbol]
              else
                raise ArgumentError, "Attribute #{symbol} is not defined!" unless auto_vivifiy_on_read
              end
            else
              key_to_set = symbol.to_s[/^(.+)=$/, 1] || symbol
              self[key_to_set] = (args.length == 1 ? args[0] : args)
            end
          end