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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 _link_replace(self, match, **context):
 """ Callback for re.sub to replace link text with markup. Turns out using a callback function is actually faster than using backrefs, plus this lets us provide a hook for user customization. linker_takes_context=True means that the linker gets passed context like a standard format function. """

        url = match.group(0)
        if self.linker:
            if self.linker_takes_context:
                return self.linker(url, context)
            else:
                return self.linker(url)
        else:
            href = url
            if '://' not in href:
                href = 'http://' + href
            # Escape quotes to avoid XSS, let the browser escape the rest.
            return self.url_template.format(href=href.replace('"', '%22'), text=url)