class Base:
  symbol: str
  
  def __init__(self, symbol, store):
    self.symbol = symbol
    self.store = store
    
  def path(self):
    raise NotImplementedError('path')
    
  def ext(self):
    raise NotImplementedError('extension')
  
  def type(self):
    return self.__class__.__name__
  
  def __str__(self):
    return f'{self.symbol}.{self.ext()}'