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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 fetch_uri_contents(self, uri: str) -> URI: """ Return content-addressed URI stored at registry URI. """

        address, pkg_name, pkg_version = parse_registry_uri(uri)
        self.w3.enable_unstable_package_management_api()
        self.w3.pm.set_registry(address)
        _, _, manifest_uri = self.w3.pm.get_release_data(pkg_name, pkg_version)
        return manifest_uri