loss curve — v1  (final train 1.5122, val 1.5198 @ iter 19500)
 2.829 |*                                                               
 2.751 |                                                                
 2.674 |                                                                
 2.596 |                                                                
 2.519 |                                                                
 2.441 |                                                                
 2.364 |  *                                                             
 2.286 |                                                                
 2.209 |                                                                
 2.132 |   *                                                            
 2.054 |                                                                
 1.977 |     *                                                          
 1.899 |       **                                                       
 1.822 |          * **                                                  
 1.744 |             . * ** *                                           
 1.667 |                    . ** * ** * *                               
 1.590 |                                 * ** * ** * ** *               
 1.512 |                                                  ** * ** * ** *
       +----------------------------------------------------------------
        500                                                        19500
  legend: '.' train   '*' val   (x: iter, y: loss)