BUG: wrong doc or wrong connectby?

PG 8.3.1

http://www.postgresql.org/docs/8.3/interactive/tablefunc.html
I have used copy/past,
examples about does not work (

CREATE TABLE connectby_tree(keyid text, parent_keyid text, pos int);

INSERT INTO connectby_tree VALUES('row1',NULL, 0);
INSERT INTO connectby_tree VALUES('row2','row1', 0);
INSERT INTO connectby_tree VALUES('row3','row1', 0);
INSERT INTO connectby_tree VALUES('row4','row2', 1);
INSERT INTO connectby_tree VALUES('row5','row2', 0);
INSERT INTO connectby_tree VALUES('row6','row4', 0);
INSERT INTO connectby_tree VALUES('row7','row3', 0);
INSERT INTO connectby_tree VALUES('row8','row6', 0);
INSERT INTO connectby_tree VALUES('row9','row5', 0);

SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0, '~')
AS t(keyid text, parent_keyid text, level int, branch text);

42883
ERROR: function connectby(unknown, unknown, unknown, unknown, integer, unknown) does not exists
Character: 15
HINT: No function matches the given name and argument types. You might need to add explicit type casts.