title: conditional string in format string (f"{...}")
body: <p>As you know over Python 3.6, there is a feature known as <a href="https://realpython.com/python-f-strings/" rel="nofollow noreferrer">format string literals</a>. <code>str(obj['my_str_index'])</code> can be either <code>None</code> or a string value. I've tried the below one but it doesn't yield <code>'null'</code> text if it is <code>None</code>.</p>
  
  <pre><code>foo = "soner test " \
  f"{str(obj['my_str_index']) if str(obj['my_str_index']) is not None else 'null'}
  </code></pre>