title: What is a value called, that signals that nothing has happened?
body: <p>I'm at a loss for what to call that or even what to search for.</p>
  
  <p>What I'm looking for is something like this:</p>
  
  <pre><code>value = None
  
  if something_is_true:
      value = 123
  
  if value is not None:
      send(value)
  </code></pre>
  
  <p>What is the use of <code>None</code> called in this instance? In my head it sounds something like Cardinal Value, although that is not it.</p>