the worthless code in the file uvm_callback.sv

Hi, all

    There is  a piece of code in the function m_add_tw_cbs of the uvm_typed_callbacks#(type T=uvm_object) of the file uvm_callback.sv as follow:

        if(m_t_inst.m_pool.first(obj)) begin
      do begin
        if($cast(me,obj)) begin
          q = m_t_inst.m_pool.get(obj);
          if(q==null) begin
            q=new;
            m_t_inst.m_pool.add(obj,q);
          end
          if(m_cb_find(q,cb) == -1) begin
            if(ordering == UVM_APPEND)
              q.push_back(cb);
            else
              q.push_front(cb);
          end
        end
      end while(m_t_inst.m_pool.next(obj));
    end

   I want to know whether the red piece is worthless ?

   Thank you in advanced!

BR

QIN