Destructive nature operation in python?
<blockquote>
  <p><strong>Possible Duplicate:</strong><br>
  <a href="http://stackoverflow.com/questions/2612802/how-to-clone-a-list-in-python">How to clone a list in python?</a>  </p>
</blockquote>



<p>I found some interesting results</p>

<pre><code>a = [1, 2] 
b=a 
b.append(3) 
print a, b

#=&gt; [1,2,3] [1,2,3]


a = [1, 2] 
b=a 
b += [3] 
print a, b

#=&gt; [1,2] [1,2,3]
</code></pre>

<p>It seems like some operation have change the referenced value, some create  a new. I remember in Ruby it can use <code>!</code> to indicate which method have this destructive nature. Does python have the similar way to let me distinguish them? or providing a list to show all the most commonly used one?</p>
