ROOT (token: short_text [lag_newlines/spaces] {pos_id})
 ¦--expr: x [0/0] {2}                                  
 ¦   °--SYMBOL: x [0/0] {1}                            
 ¦--expr: 1+1 [1/0] {3}                                
 ¦   ¦--expr: 1 [0/0] {5}                              
 ¦   ¦   °--NUM_CONST: 1 [0/0] {4}                     
 ¦   ¦--'+': + [0/0] {6}                               
 ¦   °--expr: 1 [0/0] {8}                              
 ¦       °--NUM_CONST: 1 [0/0] {7}                     
 °--expr: y + ( [1/0] {9}                              
     ¦--expr: y [0/1] {11}                             
     ¦   °--SYMBOL: y [0/0] {10}                       
     ¦--'+': + [0/1] {12}                              
     °--expr: (
2*  [0/0] {13}                        
         ¦--'(': ( [0/0] {14}                          
         ¦--expr: 2* z [1/0] {15}                      
         ¦   ¦--expr: 2 [0/0] {17}                     
         ¦   ¦   °--NUM_CONST: 2 [0/0] {16}            
         ¦   ¦--'*': * [0/1] {18}                      
         ¦   °--expr: z [0/0] {20}                     
         ¦       °--SYMBOL: z [0/0] {19}               
         °--')': ) [1/0] {21}                          
