    def scroll(self, lines=1):
        """
        Scroll the abstract canvas up one line.

        :param lines: The number of lines to scroll.  Defaults to down by one.
        """
        self._buffer.scroll(lines)
        self._start_line += lines
Scroll the abstract canvas up one line.

:param lines: The number of lines to scroll.  Defaults to down by one.
asciimatics/screen.py