anchor.diff:      | 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)
  +    | 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)
       | FLOOR OPEN_BRACE expression CLOSE_BRACE -> ^(FLOOR expression)
  
positive.code:     | SECONDS OPEN_BRACE expression CLOSE_BRACE -> ^(SECONDS expression)
      | TIMEZONE OPEN_BRACE expression CLOSE_BRACE -> ^(TIMEZONE expression)
      | TZ OPEN_BRACE expression CLOSE_BRACE -> ^(TZ expression)
      | NOW nil -> ^(NOW)
      | MD5 OPEN_BRACE expression CLOSE_BRACE -> ^(MD5 expression)
      | SHA1 OPEN_BRACE expression CLOSE_BRACE -> ^(SHA1 expression)
      | SHA224 OPEN_BRACE expression CLOSE_BRACE -> ^(SHA224 expression)
  
negative.code:     ;
      
  modify
      : ( WITH i=iriRef )? (deleteClause insertClause? | insertClause) usingClause* WHERE groupGraphPattern -> ^(MODIFY ^(WITH $i)? deleteClause* insertClause* usingClause* ^(WHERE groupGraphPattern))
      ;
    
  deleteClause
  