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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 get_url(self, fname):
 """ Get the full URL to download a file in the registry. Parameters fname : str The file name (relative to the *base_url* of the remote data storage) to fetch from the local storage. """

        self._assert_file_in_registry(fname)
        return self.urls.get(fname, "".join([self.base_url, fname]))