Writes a definition list into the buffer.  This is how options
        and commands are usually formatted.

        :param rows: a list of two item tuples for the terms and values.
        :param col_max: the maximum width of the first column.
        :param col_spacing: the number of spaces between the first and
                            second column.

def write_dl(self, rows, col_max=30, col_spacing=2):
        """Writes a definition list into the buffer.  This is how options
        and commands are usually formatted.

        :param rows: a list of two item tuples for the terms and values.
        :param col_max: the maximum width of the first column.
        :param col_spacing: the number of spaces between the first and
                            second column.
        """
        rows = list(rows)
        widths = measure_table(rows)
        if len(widths) != 2:
            raise TypeError('Expected two columns for definition list')

        first_col = min(widths[0], col_max) + col_spacing

        for first, second in iter_rows(rows, len(widths)):
            self.write('%*s%s' % (self.current_indent, '', first))
            if not second:
                self.write('\n')
                continue
            if term_len(first) <= first_col - col_spacing:
                self.write(' ' * (first_col - term_len(first)))
            else:
                self.write('\n')
                self.write(' ' * (first_col + self.current_indent))

            text_width = max(self.width - first_col - 2, 10)
            lines = iter(wrap_text(second, text_width).splitlines())
            if lines:
                self.write(next(lines) + '\n')
                for line in lines:
                    self.write('%*s%s\n' % (
                        first_col + self.current_indent, '', line))
            else:
                self.write('\n')