code: def GetHelper(cls, type_indicator):
      
      if type_indicator not in cls._resolver_helpers:
        raise KeyError(
            'Resolver helper not set for type indicator: {0:s}.'.format(
                type_indicator))
  
      return cls._resolver_helpers[type_indicator]
docs: Retrieves the path specification resolver helper for the specified type.
  
      Args:
        type_indicator (str): type indicator.
  
      Returns:
        ResolverHelper: a resolver helper.
  
      Raises:
        KeyError: if resolver helper is not set for the corresponding type
            indicator.