Replace all lines matching `old_line` with `new_line`.

        If ``once`` is set to True, remove only the first instance.

        Returns:
            int: the number of updates performed

def update_line(self, section, old_line, new_line, once=False):
        """Replace all lines matching `old_line` with `new_line`.

        If ``once`` is set to True, remove only the first instance.

        Returns:
            int: the number of updates performed
        """
        try:
            s = self._get_section(section, create=False)
        except KeyError:
            return 0
        return s.update(old_line, new_line, once=once)