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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 message(self):
 """ Render the body of the message to a string. """

        template_name = self.template_name() if \
            callable(self.template_name) \
            else self.template_name
        return loader.render_to_string(
            template_name, self.get_context(), request=self.request
        )