ROOT (token: short_text [lag_newlines/spaces] {pos_id})
 °--expr:  [0/0] {1}                                   
     ¦--expr:  [0/1] {3}                               
     ¦   °--SYMBOL: a [0/0] {2}                        
     ¦--LEFT_ASSIGN: <- [0/1] {4}                      
     °--expr:  [0/0] {5}                               
         ¦--'{': { [0/0] {6}                           
         ¦--expr:  [0/0] {7}                           
         ¦   ¦--expr:  [0/0] {9}                       
         ¦   ¦   °--NUM_CONST: 1 [0/0] {8}             
         ¦   ¦--'+': + [0/0] {10}                      
         ¦   °--expr:  [0/0] {12}                      
         ¦       °--NUM_CONST: 1 [0/0] {11}            
         °--'}': } [0/0] {13}                          
