def header_check(self, content):
        """Special HTML encoding check."""

        encode = None

        # Look for meta charset
        m = RE_HTML_ENCODE.search(content)
        if m:
            enc = m.group(1).decode('ascii')

            try:
                codecs.getencoder(enc)
                encode = enc
            except LookupError:
                pass
        else:
            encode = self._has_xml_encode(content)
        return encode
Special HTML encoding check.