title: Serialize an already serialized json string?
body: <p>I have a function writing data to a cache, where the data must be serialized to a json-formatted string. Rather than checking to see if the input <code>data</code> is a valid json string (i.e. try-except statement), can I simply always call <code>json.dumps(data)</code>? That is, if the input <code>data</code> is already serialized to json format, is calling <code>json.dumps(data)</code> harmless?</p>