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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 _prepare_template(self, obj, needs_request=False):
 """ This is a copy of CharField.prepare_template, except that it adds a fake request to the context, which is mainly needed to render CMS placeholders """

        if self.instance_name is None and self.template_name is None:
            raise SearchFieldError("This field requires either its instance_name variable to be populated or an explicit template_name in order to load the correct template.")

        if self.template_name is not None:
            template_names = self.template_name

            if not isinstance(template_names, (list, tuple)):
                template_names = [template_names]
        else:
            template_names = ['search/indexes/%s/%s_%s.txt' % (obj._meta.app_label, obj._meta.module_name, self.instance_name)]

        t = loader.select_template(template_names)
        ctx = {'object': obj}
        if needs_request:
            request = rf.get("/")
            request.session = {}
            ctx['request'] = request
        return t.render(Context(ctx))