def marker_for_line(self, line):
        """
        Returns the marker that is displayed at the specified line number if
        any.

        :param line: The marker line.

        :return: Marker of None
        :rtype: pyqode.core.Marker
        """
        block = self.editor.document().findBlockByNumber(line)
        try:
            return block.userData().messages
        except AttributeError:
            return []
Returns the marker that is displayed at the specified line number if
        any.

        :param line: The marker line.

        :return: Marker of None
        :rtype: pyqode.core.Marker