How to fix Cursor does not exist in PostgreSQL

BEGIN;
DECLARE my_cursor CURSOR FOR SELECT * FROM users;
FETCH NEXT FROM my_cursor;
CLOSE my_cursor;
COMMIT;

DECLARE my_cursor CURSOR WITH HOLD FOR SELECT * FROM users;
COMMIT;  -- Cursor survives this commit
FETCH NEXT FROM my_cursor;  -- Works in a new transaction
CLOSE my_cursor;  -- Must explicitly close when done

conn = psycopg2.connect(dsn)
conn.autocommit = False  # Ensure transactions are not auto-committed
cur = conn.cursor()
cur.execute("BEGIN")
cur.execute("DECLARE my_cursor CURSOR FOR SELECT * FROM users")
cur.execute("FETCH NEXT FROM my_cursor")
conn.commit()

$pdo = new PDO("pgsql:dbname=mydb", $user, $pass);
$pdo->setAttribute(PDO::ATTR_AUTOCOMMIT, false);
$pdo->beginTransaction();
$pdo->exec("DECLARE my_cursor CURSOR FOR SELECT * FROM users");
// ... fetch from cursor
$pdo->commit();

-- WRONG: Cursor is closed before fetch
DECLARE my_cursor CURSOR FOR SELECT * FROM users;
CLOSE my_cursor;
FETCH NEXT FROM my_cursor;  -- Error: cursor does not exist

-- CORRECT: Fetch first, then close
DECLARE my_cursor CURSOR FOR SELECT * FROM users;
FETCH NEXT FROM my_cursor;
CLOSE my_cursor;

CREATE FUNCTION fetch_users() RETURNS SETOF users AS $$
DECLARE
  my_cursor CURSOR FOR SELECT * FROM users;
  user_row users;
BEGIN
  OPEN my_cursor;
  LOOP
    FETCH my_cursor INTO user_row;
    EXIT WHEN NOT FOUND;
    RETURN NEXT user_row;
  END LOOP;
  CLOSE my_cursor;
END;
$$ LANGUAGE plpgsql;