Return a sequence of str values representing the text in
        *line_source* wrapped within this fitter when rendered at
        *point_size*.

def _wrap_lines(self, line_source, point_size):
        """
        Return a sequence of str values representing the text in
        *line_source* wrapped within this fitter when rendered at
        *point_size*.
        """
        text, remainder = self._break_line(line_source, point_size)
        lines = [text]
        if remainder:
            lines.extend(self._wrap_lines(remainder, point_size))
        return lines