    # File lib/fog/ecloud/mock_data_classes.rb, line 550
            def <<(disk)
              next_address = 0
              disk_with_max_address = max {|a, b| a[:address] <=> b[:address] }
              disk_with_max_address && next_address = disk_with_max_address.address + 1
              disk[:address] ||= next_address

              super(disk)

              if (addresses = map {|d| d.address }).uniq.size != size
                raise "Duplicate disk address in: #{addresses.inspect} (#{size})"
              end

              sort! {|a, b| a.address <=> b.address }
              self
            end