ROOT (token: short_text [lag_newlines/spaces] {pos_id})
 °--expr: 1 +
  [0/0] {1}                             
     ¦--expr: 1 [0/1] {4}                              
     ¦   °--NUM_CONST: 1 [0/0] {3}                     
     ¦--'+': + [0/13] {5}                              
     ¦--expr: 2 [1/1] {7}                              
     ¦   °--NUM_CONST: 2 [0/0] {6}                     
     ¦--'+': + [0/1] {8}                               
     °--expr: (
3 + [0/0] {9}                         
         ¦--'(': ( [0/0] {10}                          
         ¦--expr: 3 + 4 [1/0] {11}                     
         ¦   ¦--expr: 3 [0/1] {13}                     
         ¦   ¦   °--NUM_CONST: 3 [0/0] {12}            
         ¦   ¦--'+': + [0/1] {14}                      
         ¦   °--expr: 4 [0/0] {16}                     
         ¦       °--NUM_CONST: 4 [0/0] {15}            
         °--')': ) [0/0] {17}                          
