title: Python append json object in file, guard if object does not exist
body: <p>I am reading in a json file using python, and then appending in an array within an object, the shape of this being </p>
  
  <pre><code>"additional_info": {"other_names": ["12.13"]
  </code></pre>
  
  <p>I am appending the array as follows:</p>
  
  <pre><code>data["additional_info"]["other_names"].append('13.9')
  with open('jsonfile', 'w') as f:
      json.dump(data, f)
  </code></pre>
  
  <p>I want to set a guard to check if additional_info and other_names exists in the json file and if it doesn't then to create it. How would I go about doing this?</p>