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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 set_cache_url (self):
 """Set the URL to be used for caching."""

        # remove anchor from cached target url since we assume
        # URLs with different anchors to have the same content
        self.cache_url = urlutil.urlunsplit(self.urlparts[:4]+[u''])
        if self.cache_url is not None:
            assert isinstance(self.cache_url, unicode), repr(self.cache_url)