def to_notebook(self, s, **kwargs):
        """Convert the markdown string s to an IPython notebook.

        Returns a notebook.
        """
        all_blocks = self.parse_blocks(s)
        if self.pre_code_block['content']:
            # TODO: if first block is markdown, place after?
            all_blocks.insert(0, self.pre_code_block)

        blocks = [self.process_code_block(block) for block in all_blocks]

        cells = self.create_cells(blocks)

        nb = nbbase.new_notebook(cells=cells)

        return nb
Convert the markdown string s to an IPython notebook.

        Returns a notebook.