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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 send_preview(self, recipients, personalize="fallback"):
 """Sends a preview of this campaign."""

        body = {
            "PreviewRecipients": [recipients] if isinstance(recipients, str) else recipients,
            "Personalize": personalize}
        response = self._post(self.uri_for("sendpreview"), json.dumps(body))