code: def is_valid_single_address(self, single_address):
      
      if not isinstance(single_address, SingleAddress):
        raise TypeError(
          'Parameter "{}" is of type {}, expecting type {}.'.format(
            single_address, type(single_address), SingleAddress))
  
      try:
        return bool(self.scan_specs([single_address]))
      except AddressLookupError:
        return False
docs: Check if a potentially ambiguous single address spec really exists.
  
      :param single_address: A SingleAddress spec.
      :return: True if given spec exists, False otherwise.