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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 get_signal_models(self):
 """Return all signal types in a list. :rtype: list(`signal-model`) """


        base = self.db.Model
        return [
            cls for cls in base._decl_class_registry.values() if (
                isinstance(cls, type)
                and issubclass(cls, base)
                and hasattr(cls, 'send_signalbus_message')
            )
        ]