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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _parse_tag(self):
 """Parse an HTML tag at the head of the wikicode string."""

        reset = self._head
        self._head += 1
        try:
            tag = self._really_parse_tag()
        except BadRoute:
            self._head = reset
            self._emit_text("<")
        else:
            self._emit_all(tag)