How to specify "nullable" return type with type hints
<p>Suppose I have a function:</p>

<pre><code>def get_some_date(some_argument: int=None) -&gt; %datetime_or_None%:
    if some_argument is not None and some_argument == 1:
        return datetime.utcnow()
    else:
        return None
</code></pre>

<p>How do I specify the return type for something that can be <code>None</code>?</p>