def header_id_from_text(self, text, prefix, n):
        """Generate a header id attribute value from the given header
        HTML content.

        This is only called if the "header-ids" extra is enabled.
        Subclasses may override this for different header ids.

        @param text {str} The text of the header tag
        @param prefix {str} The requested prefix for header ids. This is the
            value of the "header-ids" extra key, if any. Otherwise, None.
        @param n {int} The <hN> tag number, i.e. `1` for an <h1> tag.
        @returns {str} The value for the header tag's "id" attribute. Return
            None to not have an id attribute and to exclude this header from
            the TOC (if the "toc" extra is specified).
        """
        header_id = _slugify(text)
        if prefix and isinstance(prefix, base_string_type):
            header_id = prefix + '-' + header_id
        if self._count_from_header_id in header_id:
            self._count_from_header_id[header_id] += 1
            header_id += '-%s' % self._count_from_header_id[header_id]
        else:
            self._count_from_header_id[header_id] = 1
        return header_id
dataset/ETHPy150Open an0/Letterpress/code/markdown2/lib/markdown2.py/Markdown.header_id_from_text/swapped operands of `in`