code: def push(object)
        item = coerce_item object
  
        if empty?
          @_chain = item
        else
          list_tail.append item
        end
  
        self
      end
docs: Insert an item at the end of the list. If the given object is not an
   object responding to #item it will be treated as a value. The value will
   be wraped in a new Item create by #create_item.
  
   See Item#append for more details.
  
   @param object [#item, Object] the item to insert, or an arbitrary object.
   @return [self]