anchor.diff:  
   blankNode
       : BLANK_NODE_LABEL
  -    | OPEN_SQUARE_BRACE CLOSE_SQUARE_BRACE
  -    ;
  -
  +    | anon
  +    ;
  +
  +anon
  +    : OPEN_SQUARE_BRACKET CLOSE_SQUARE_BRACKET
  +    ;	
   // $>
   
   // $<Lexer
  
positive.code: DOUBLE_NEGATIVE
      : MINUS DOUBLE
      ;
  
  fragment
  EXPONENT
      : ('e'|'E') (PLUS|MINUS)? DIGIT+
      ;
  
  STRING_LITERAL1
      : '\'' ( options {greedy=false;} : ~('\u0027' | '\u005C' | '\u000A' | '\u000D') | ECHAR )* '\''
      ;
  
  STRING_LITERAL2
      : '"'  ( options {greedy=false;} : ~('\u0022' | '\u005C' | '\u000A' | '\u000D') | ECHAR )* '"'
      ;
  
  STRING_LITERAL_LONG1
  
negative.code:     ;
  
  var
      : VAR1 | VAR2
      ;
  
  graphTerm
  