text: import abc
  
  
  class Player(metaclass=abc.ABCMeta):
      @abc.abstractmethod
      def root(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def isRoot(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def isExternal(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def isInternal(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def size(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def clearPath(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def updatePath(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def select(cls):
          return NotImplemented
  
      @abc.abstractmethod
      def expand(cls):
          return NotImplemented
  