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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_def_models(self, definition_filter=None):
 """ Used for class based definitions """

        model_filter = definition_filter or (lambda tag: True)
        return {
            definition.name: definition.obj
            for definition in self.definition_models
            if model_filter(definition)
        }