title: Type Hinting: Argument Of Type Class
body: <p>I'm defining a method</p>
  <pre><code>def foo_my_class(my_class: ???, bar: str) -&gt; None:
      &quot;&quot;&quot; Operate on my_class &quot;&quot;&quot;
  </code></pre>
  <p>I wonder, how can I use type hinting feature to specify that class should be passed in the first argument.</p>
  <p>Basically, what should I put instead of <code>???</code> mark up there?</p>
  <p>Here is some more code to be more specific on what I am trying to achieve.</p>
  <pre><code>class Base(object):
     &quot;&quot;&quot;base class&quot;&quot;&quot;
  
  class X(Base):
      &quot;&quot;&quot;some class&quot;&quot;&quot;
  
  class Y(Base):
      &quot;&quot;&quot;some other class&quot;&quot;&quot;   
  
  foo_my_class(X, &quot;foo&quot;)    
  foo_my_class(Y, &quot;bar&quot;)
  </code></pre>