def date_line_to_text(self, date_line):
        """
        Return the textual representation of the given :class:`~taxi.timesheet.lines.DateLine` instance. The date
        format is set by the `date_format` parameter given when instanciating the parser instance.
        """
        # Changing the date in a dateline is not supported yet, but if it gets implemented someday this will need to be
        # changed
        if date_line._text is not None:
            return date_line._text
        else:
            return date_utils.unicode_strftime(date_line.date, self.date_format)