# File lib/mongo/operation/update/bulk_result.rb, line 62
        def n_matched
          return 0 unless acknowledged?
          @replies.reduce(0) do |n, reply|
            if upsert?(reply)
              reply.documents.first[N] - n_upserted
            else
              if reply.documents.first[N]
                n += reply.documents.first[N]
              else
                n
              end
            end
          end
        end