Available methods :
List <String > getCategories ( )
> Returns list of available categories.
ItemStack getHead ( int id )
> Returns head with the id associated. Returns null if not valid head id.
boolean openCategories (Player player )
> Opens categories GUI for player. Returns whether success or not.
boolean openHeads (Player player, String category, int page )
> Opens heads gui for player with the selected category and page. Return whether success or not.
ItemStack getRandomHead ( )
> Returns a random head.
ItemStack getRandomHead ( String category )
> Returns random head in category. Returns null if category is not valid.
List <Integer > getHeadsIds ( )
> Returns list of heads ids.
List <Integer > getHeadsIds ( String category )
> Returns list of heads ids in category. Returns null if category is not valid.
List <Integer > searchHeads ( String search )
> Returns list of heads ids that includes search term in name.
List <Integer > searchHeads ( String search, boolean includeTags )
>  Returns list of heads ids that includes search term in name and tags.
boolean searchHeads (Player player, String search, boolean includeTags )
> Open search GUI for player. (Returns false if error or matches not found )

Available events :
HeadPurchaseEvent
> When player purchases /get a head from heads GUI.