docs: def _fill(self, data, total_length, padding_symbol):
  		""" Overridden :meth:`.WSimplePadding._fill` method. This methods adds padding symbol at the beginning
  		and at the end of the specified data.
  
  		:param data: data to append to
  		:param total_length: target length
  		:param padding_symbol: symbol to pad
  		:return: bytes
  		"""
  
  		delta = total_length - len(data)
  		return ((padding_symbol * random_int(delta)) + data).ljust(total_length, padding_symbol)