data = new Integer(4);
L.add( data );
==> ignore = new Node( data , m_head.m_prev );


 L  m_head                        m_data = data;
Ŀ Ŀ
*>x
                    prev          this
Ŀ
 Ŀ    Ŀ    Ŀ      Ŀ
>  *>  *>  *       0
*. <*. <*. <     0. 
               
        
                                      
    / \        / \        / \           / \
    1        2        3           4 
    \_/        \_/        \_/           \_/

                                  this.m_next = prev.m_next;
                                  this.m_prev = prev;
                                  prev.m_next = this;
 L  m_head
Ŀ Ŀ
*>x
                    prev          this
<Ŀ
 Ŀ    Ŀ    Ŀ       Ŀ 
>  *>  *>  *>  *
*. <*. <*. <<*. 
               
        
                                      
    / \        / \        / \           / \
    1        2        3           4 
    \_/        \_/        \_/           \_/

                                  m_next.m_prev = this;
 L  m_head
Ŀ Ŀ
*>x
                    prev          this
Ŀ
 Ŀ    Ŀ    Ŀ       Ŀ 
>  *>  *>  *>  *
*. <*. <*. <ĳ*. <
                 

                                      
    / \        / \        / \           / \
    1        2        3           4 
    \_/        \_/        \_/           \_/

                                  m_next.m_prev = this;
