How to use recursion to calculate the max length of a nested list?
<p>Here is the code that counts the maximum length in a nested list.</p>

<pre><code>def max_length(obj):
    """
    Return the maximum length of obj or any of its sublists, if obj is a list.
    otherwise return 0.

    @param object|list obj: object to return length of
    @rtype: int

    &gt;&gt;&gt; max_length(17)
    0
    &gt;&gt;&gt; max_length([1, 2, 3, 17])
    4
    &gt;&gt;&gt; max_length([[1, 2, 3, 3], 4, [4, 5]])
    4
    """
    if isinstance(obj,int):
        return 0
    else:
        return max([len(x) for x in obj])
</code></pre>

<p>The code is wrong as I don't know how to correctly combine <code>len()</code> function and recursion. What should I do?</p>