anchor.diff:  grammar JSON5;
   
   json5
  -   : value
  +   : value? EOF
      ;
   
   obj
  
positive.code:    : [\p{L}]
     | '$'
     | '_'
     | UNICODE_ESC
     ;
  
  fragment IDENTIFIER_PART
  
negative.code:    | IDENTIFIER
     ;
  
  value
     : STRING
     | NUMBER
     | obj
     | arr
     | 'true'
  