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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 controller(self):
 """Show current linked controllers."""

        if hasattr(self, 'controllers'):
            if len(self.controllers) > 1:
                # in the future, we should support more controllers
                raise TypeError("Only one controller per account.")
            return self.controllers[0]
        raise AttributeError("There is no controller assigned.")