    link.isLink()

Always returns `true`. The reason the method is here is that both `joint.dia.Element` and `joint.dia.Link` inherit from `joint.dia.Cell`. This method is useful if you don't know what the cell is. Calling `el.isLink()` is equivalent to `el instanceof joint.dia.Link`. Example:

    var cell = graph.getCell(myId)
    if (cell.isLink()) {
        // Do something if the cell is a link.
    }