anchor.diff:      ;
   
   subSelect
  -    : selectClause whereClause solutionModifier	-> ^(SUBSELECT whereClause* solutionModifier)
  +    : selectClause whereClause solutionModifier	-> ^(SUBSELECT whereClause* solutionModifier*)
       ;
       	
   selectClause
  
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: 
  NOW : ('N'|'n')('O'|'o')('W'|'w');
  
  MD5 : ('M'|'m')('D'|'d')'5';
  
  SHA1 : ('S'|'s')('H'|'h')('A'|'a')'1';
  
  