return nil // channel elements are not identical.
		}
		if ch.Dir() == types.SendRecv {
			// ch is bidirectional. We can safely always use curr's direction.
			ch = curr
		} else if curr.Dir() != types.SendRecv && ch.Dir() != curr.Dir() {
			// ch and curr are not bidirectional and not the same direction.
			return nil
		}
	}
	return ch
}