code: def register(style, func=None):
      
      if func is not None:
          _registry[style] = func
          return
  
      def decorator(func):
          _registry[style] = func
  
          @wraps(func)
          def wrapper(pinyin, **kwargs):
              return func(pinyin, **kwargs)
  
          return wrapper
      return decorator
docs: 注册一个拼音风格实现
  
      ::
  
          @register('echo')
          def echo(pinyin, **kwargs):
              return pinyin
  
          # or
          register('echo', echo)