ROOT (token: short_text [lag_newlines/spaces] {pos_id})     
 °--expr:  [0/0] {1}                                        
     ¦--expr:  [0/0] {3}                                    
     ¦   ¦--expr:  [0/0] {4}                                
     ¦   ¦   ¦--expr:  [0/2] {5}                            
     ¦   ¦   ¦   ¦--expr:  [0/0] {6}                        
     ¦   ¦   ¦   ¦   ¦--expr:  [0/0] {8}                    
     ¦   ¦   ¦   ¦   ¦   °--SYMBOL: x [0/0] {7}             
     ¦   ¦   ¦   ¦   ¦--'$': $ [0/3] {9}                    
     ¦   ¦   ¦   ¦   °--SYMBOL_FUNCTION_CALL: add [1/0] {10}
     ¦   ¦   ¦   ¦--'(': ( [0/0] {11}                       
     ¦   ¦   ¦   ¦--expr:  [0/0] {13}                       
     ¦   ¦   ¦   ¦   °--NUM_CONST: 10 [0/0] {12}            
     ¦   ¦   ¦   °--')': ) [0/0] {14}                       
     ¦   ¦   ¦--'$': $ [0/0] {15}                           
     ¦   ¦   °--SYMBOL_FUNCTION_CALL: add [1/0] {16}        
     ¦   ¦--'(': ( [0/0] {17}                               
     ¦   ¦--expr:  [0/0] {19}                               
     ¦   ¦   °--NUM_CONST: 10 [0/0] {18}                    
     ¦   °--')': ) [0/0] {20}                               
     ¦--'$': $ [0/0] {21}                                   
     ¦--SYMBOL: sum [0/1] {22}                              
     ¦--'+': + [0/0] {23}                                   
     °--expr:  [1/0] {25}                                   
         °--NUM_CONST: 3 [0/0] {24}                         
