How to specify a method argument must be of certain class
<p>So I have a class like this:</p>

<pre><code> class Encoder(object):

     movie = None

     def __init__(self, movie_instance):
         self.movie = movie_instance

     def encode_profile_hd(self):
         print "profile 1"

     def encode_profile_sd(self):
         print "profile 2"
</code></pre>

<p>How can I specify the movie_instance argument passed to the constructor must be of Movie class?</p>

<p>I tried:</p>

<pre><code>def __init__(self, Movie movie_instance):
</code></pre>

<p>But that doesn't work. Sorry if this is obvious.</p>
