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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 profile_pic_url(self) -> str: """Return URL of profile picture. If logged in, the HD version is returned, otherwise a lower-quality version. .. versionadded:: 4.0.3 .. versionchanged:: 4.2.1 Require being logged in for HD version (as required by Instagram)."""

        if self._context.is_logged_in:
            try:
                return self._iphone_struct['hd_profile_pic_url_info']['url']
            except (InstaloaderException, KeyError) as err:
                self._context.error('{} Unable to fetch high quality profile pic.'.format(err))
                return self._metadata("profile_pic_url_hd")
        else:
            return self._metadata("profile_pic_url_hd")