Python count sub lists in nested list
<p>I have created a list  -></p>

<pre><code>a = [[1,2,3],[4,5,6],[7,8,9]]
</code></pre>

<p>1) How do I get the count of number of sub-lists in a?
Like in this case it is 3</p>

<p>2) I am using iterator tool chain for traversing this list</p>

<pre><code> for elt in itertools.chain.from_iterable(node):
</code></pre>

<p>Is there any way to know if I have traversed a sub list ?</p>
