docs: def to_string(address, leading_dot=False):
  		""" Return doted-written address by the given WFQDN object
  
  		:param address: address to convert
  		:param leading_dot: whether this function place leading dot to the result or not
  		:return: str
  		"""
  
  		if isinstance(address, WFQDN) is False:
  			raise TypeError('Invalid type for FQDN address')
  
  		result = '.'.join(address._labels)
  		return result if leading_dot is False else (result + '.')