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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 base_uri(self):
 """ Resolution base for JSON schema. Also used as the default graph ID for RDF. """

        if self._base_uri is None:
            if self._resolver is not None:
                self._base_uri = self.resolver.resolution_scope
            else:
                self._base_uri = 'http://pudo.github.io/jsongraph'
        return URIRef(self._base_uri)