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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _next_label(self):
 """Helper method to move to the next label. Not intended for external use. This does not increment the label_count attribute as the next label may not be usable (it may have been marked as missing through partial_pages). See _next_unused_label for generally more useful method. """

        # Special case for the very first label.
        if self.page_count == 0:
            self._new_page()

        # Filled up a page.
        elif self._position == self._numlabels:
            self._new_page()

        # Filled up a row.
        elif self._position[1] == self.specs.columns:
            self._position[0] += 1
            self._position[1] = 0

        # Move to the next column.
        self._position[1] += 1