   @param {Element|jQuery|String} elementOrSelector
   @param {String} [options.url]
   @param {String} [options.position='bottom-right']
+    Defines where the popup is attached to the opening element.
+
+    Valid values are `bottom-right`, `bottom-left`, `top-right` and `top-left`.
   @param {String} [options.animation]
     The animation to use when opening the popup.
   @param {Number} [options.duration]

        top: linkBox.top + linkBox.height
      when "bottom-left"
        left: linkBox.left
        top: linkBox.bottom + linkBox.height
      when "top-right"
        right: linkBox.right
        bottom: linkBox.top

      <a href="/settings" up-popup=".options" up-sticky>Settings</a>

  @selector a[up-popup]
  @param [up-position]
    Defines where the popup is attached to the opening element.

    Valid values are `bottom-right`, `bottom-left`, `top-right` and `top-left`.
  @param [up-sticky]
    If set to `true`, the popup remains
    open even if the page changes in the background.
  @stable
  ###
  up.on('click', 'a[up-popup]', (event, $link) ->
