API IsAddOnLoaded

Returns whether an addon has been loaded. loaded, finished = IsAddOnLoaded(index or "name")

Arguments
or
 * index : Integer - The index of the addon in the user's addon list. You cannot query Blizzard-provided AddOns using this parameter.
 * name : String - The name of the addon to be queried. You can query Blizzard-provided addon using this parameter.

Returns

 * loaded : Flag - 1 if the addon has been, or is being loaded, nil otherwise.
 * finished : Flag - 1 if the addon has finished loading (the has already been fired for this addon), nil otherwise.