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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 add_link(self, link):
 """Add a Link. :type link: :class: `~opencensus.trace.link.Link` :param link: A Link object. """

        if isinstance(link, link_module.Link):
            self.links.append(link)
        else:
            raise TypeError("Type Error: received {}, but requires Link.".
                            format(type(link).__name__))