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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 _create_model(self, view_getter=None, source_getters=None, model_factory=None, officer=None):
 """ Creates a model from the model factory after retrieving the source and the view. The officer is the IOfficer FOR THE MODEL TO BE CREATED and NO OFFICER CHECKS ARE PERFORMED. """


        if view_getter is not None:
            d = defer.succeed(view_getter)
            d.addCallback(self._retrieve_view)
            d.addCallback(self._check_view)
        else:
            # views are inherited
            d = defer.succeed(self.model.view)

        d.addCallback(self._retrieve_model, source_getters,
                      model_factory, officer)

        d.addErrback(self._filter_errors)
        return d