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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 url(self):
 """Gets the url for the resource this model represents. It will just use the 'href' passed in to the constructor if that exists. Otherwise, it will generated it based on the collection's url and the model's identifier. """

        if self._href is not None:
            return self._href
        if self.identifier:
            #  for some reason atlas does not use classifications here in the path when considering one classification
            path = '/'.join([self.parent.url.replace('classifications/', 'classficiation/'), self.identifier])
            return path
        raise exceptions.ClientError("Not able to determine object URL")