anchor.diff:  
   NOW : ('N'|'n')('O'|'o')('W'|'w');
   
  -MD5 : ('M'|'m')('M'|'m')'5';
  +MD5 : ('M'|'m')('D'|'d')'5';
   
   SHA1 : ('S'|'s')('H'|'h')('A'|'a')'1';
   
  
positive.code:     | BOUND OPEN_BRACE var CLOSE_BRACE -> ^(BOUND var)
      | IRI OPEN_BRACE expression CLOSE_BRACE -> ^(IRI expression)
      | URI OPEN_BRACE expression CLOSE_BRACE -> ^(URI expression)
      | BNODE (OPEN_BRACE expression CLOSE_BRACE| nil) -> ^(BNODE expression)
      | RAND nil -> RAND
      | ABS OPEN_BRACE expression CLOSE_BRACE -> ^(ABS expression)
      | CEIL OPEN_BRACE expression CLOSE_BRACE -> ^(CEIL expression)
  
negative.code:     ;
  
  subSelect
      : selectClause whereClause solutionModifier	-> ^(SUBSELECT whereClause* solutionModifier*)
      ;
      	
  selectClause
  