# File lib/mongo/operation/shared/result/aggregatable.rb, line 34
        def aggregate_write_errors(count)
          return unless @replies
          @replies.reduce(nil) do |errors, reply|
            if write_errors = reply.documents.first[Error::WRITE_ERRORS]
              wes = write_errors.collect do |we|
                we.merge!('index' => count + we['index'])
              end
              (errors || []) << wes if wes
            end
          end
        end