ROOT (token: short_text [lag_newlines/spaces] {pos_id})
 ¦--expr: a[[2] [0/0] {1}                              
 ¦   ¦--expr: a [0/0] {3}                              
 ¦   ¦   °--SYMBOL: a [0/0] {2}                        
 ¦   ¦--LBB: [[ [0/0] {4}                              
 ¦   ¦--expr: 2 [0/0] {6}                              
 ¦   ¦   °--NUM_CONST: 2 [0/0] {5}                     
 ¦   ¦--']': ] [0/0] {7}                               
 ¦   °--']': ] [0/0] {8}                               
 ¦--expr: a[[2  [1/0] {9}                              
 ¦   ¦--expr: a [0/0] {11}                             
 ¦   ¦   °--SYMBOL: a [0/0] {10}                       
 ¦   ¦--LBB: [[ [0/0] {12}                             
 ¦   ¦--expr: 2 [0/1] {14}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {13}                    
 ¦   ¦--']': ] [0/0] {15}                              
 ¦   °--']': ] [0/0] {16}                              
 ¦--expr: a[[ 2 [2/0] {17}                             
 ¦   ¦--expr: a [0/0] {19}                             
 ¦   ¦   °--SYMBOL: a [0/0] {18}                       
 ¦   ¦--LBB: [[ [0/1] {20}                             
 ¦   ¦--expr: 2 [0/0] {22}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {21}                    
 ¦   ¦--']': ] [0/0] {23}                              
 ¦   °--']': ] [0/0] {24}                              
 ¦--expr: a[[ 2 [2/0] {25}                             
 ¦   ¦--expr: a [0/0] {27}                             
 ¦   ¦   °--SYMBOL: a [0/0] {26}                       
 ¦   ¦--LBB: [[ [0/1] {28}                             
 ¦   ¦--expr: 2 [0/1] {30}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {29}                    
 ¦   ¦--']': ] [0/0] {31}                              
 ¦   °--']': ] [0/0] {32}                              
 ¦--expr: a[2] [3/0] {33}                              
 ¦   ¦--expr: a [0/0] {35}                             
 ¦   ¦   °--SYMBOL: a [0/0] {34}                       
 ¦   ¦--'[': [ [0/0] {36}                              
 ¦   ¦--expr: 2 [0/0] {38}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {37}                    
 ¦   °--']': ] [0/0] {39}                              
 ¦--expr: a[2 ] [1/0] {40}                             
 ¦   ¦--expr: a [0/0] {42}                             
 ¦   ¦   °--SYMBOL: a [0/0] {41}                       
 ¦   ¦--'[': [ [0/0] {43}                              
 ¦   ¦--expr: 2 [0/1] {45}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {44}                    
 ¦   °--']': ] [0/0] {46}                              
 ¦--expr: a[ 2] [2/0] {47}                             
 ¦   ¦--expr: a [0/0] {49}                             
 ¦   ¦   °--SYMBOL: a [0/0] {48}                       
 ¦   ¦--'[': [ [0/1] {50}                              
 ¦   ¦--expr: 2 [0/0] {52}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {51}                    
 ¦   °--']': ] [0/0] {53}                              
 ¦--expr: a[ 2  [2/0] {54}                             
 ¦   ¦--expr: a [0/0] {56}                             
 ¦   ¦   °--SYMBOL: a [0/0] {55}                       
 ¦   ¦--'[': [ [0/1] {57}                              
 ¦   ¦--expr: 2 [0/1] {59}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {58}                    
 ¦   °--']': ] [0/0] {60}                              
 ¦--expr: a [[2 [3/0] {61}                             
 ¦   ¦--expr: a [0/1] {63}                             
 ¦   ¦   °--SYMBOL: a [0/0] {62}                       
 ¦   ¦--LBB: [[ [0/0] {64}                             
 ¦   ¦--expr: 2 [0/0] {66}                             
 ¦   ¦   °--NUM_CONST: 2 [0/0] {65}                    
 ¦   ¦--']': ] [0/0] {67}                              
 ¦   °--']': ] [0/0] {68}                              
 °--expr: a [1] [1/0] {69}                             
     ¦--expr: a [0/1] {71}                             
     ¦   °--SYMBOL: a [0/0] {70}                       
     ¦--'[': [ [0/0] {72}                              
     ¦--expr: 1 [0/0] {74}                             
     ¦   °--NUM_CONST: 1 [0/0] {73}                    
     °--']': ] [0/0] {75}                              
