what does 'objects being subclassable' mean?
<p><a href="http://diveintopython.org/getting_to_know_python/everything_is_an_object.html" rel="nofollow">Dive into Python</a> - </p>

<blockquote>
  <p>Different programming languages define “object” in different ways. In some, it means that all objects must have attributes and methods; in others, it means that all objects are subclassable. In Python, the definition is looser; some objects have neither attributes nor methods (more on this in Chapter 3), and not all objects are subclassable (more on this in Chapter 5). </p>
</blockquote>

<p>I am coming from <code>C++/Java</code> background. </p>
