def new_block(self):
        """
        create a new sub block to the current block and return it.
        the sub block is added to the current block.
        """
        child = Block(self, py3_wrapper=self.py3_wrapper)
        self.add(child)
        return child

        create a new sub block to the current block and return it.
        the sub block is added to the current block.
        
py3status/formatter.py