code: def add(self, data):
          
          node = LinkedListNode(data, None)
          if self._size == 0:
              self._first_node = node
              self._last_node = node
          else:
              second_node = self._first_node
              self._first_node = node
              self._first_node.update_next(second_node)
          self._size += 1
docs: Adds a new data node to the front list. The provided data will be
          encapsulated into a new instance of LinkedListNode class and linked
          list pointers will be updated, as well as list's size.
  
          :param data: the data to be inserted in the new list node
          :type data: object