anchor.diff:  PATH;
   PATH_PRIMARY;
   PATH_NEGATED;
  +UNARY_NOT;
  +UNARY_PLUS;
  +UNARY_MINUS;
  +UNARY;
   }
   
   @header {
  
positive.code: 	
  triplesNode
      : OPEN_BRACE graphNode+ CLOSE_BRACE -> ^(COLLECTION graphNode+)
      | lsb=OPEN_SQUARE_BRACKET propertyListNotEmpty[new CommonTree(new CommonToken(VAR,"[ ]"))] CLOSE_SQUARE_BRACKET -> ^(VAR[$lsb,"[ ]"] propertyListNotEmpty)
      ;
  
  graphNode
  
negative.code:     ;
  
  constraint
      : brackettedExpression
      | builtInCall
      | functionCall
      ;
  
  functionCall
  