ROOT (token: short_text [lag_newlines/spaces] {pos_id})
 ¦--COMMENT: # com [0/0] {1}                           
 ¦--COMMENT: #' sp [1/0] {2}                           
 °--expr: a [1/0] {4}                                  
     °--SYMBOL: a [0/0] {3}                            
