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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 _is_valid_url(self, url):
 """Callback for is_valid_url."""

        try:
            r = requests.head(url, proxies=self.proxy_servers)
            value = r.status_code in [200]
        except Exception as error:
            logger.error(str(error))
            value = False

        return value