:meth:`.WBlockPadding.reverse_pad` method implementation

def reverse_pad(self, data, block_size):
		""" :meth:`.WBlockPadding.reverse_pad` method implementation
		"""
		pad_byte = data[-1]
		if pad_byte > block_size:
			raise ValueError('Invalid padding')

		padding = bytes([pad_byte] * pad_byte)
		if data[-pad_byte:] != padding:
			raise ValueError('Invalid padding')

		return data[:-pad_byte]