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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 namespace_uri(self):
 """ Finds and returns first applied URI of this node that has a namespace. :return str: uri """

        try:
            return next(
                iter(filter(lambda uri: URI(uri).namespace, self._uri))
            )
        except StopIteration:
            return None