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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 _add_url(self, chunk):
 """ Add a 'url' property to a chunk and return it """

        if 'url' in chunk:
            return chunk
        public_path = chunk.get('publicPath')
        if public_path:
            chunk['url'] = public_path
        else:
            fullpath = posixpath.join(self.state.static_view_path,
                                      chunk['name'])
            chunk['url'] = self._request.static_url(fullpath)
        return chunk