Extract integer from a list
<p>I have a list like <code>['-1', '1,2,3', '2']</code> and I want to extract all the integers in it.
I don't know the number of integers in each position of the list ie the list can also be <code>['2,3,4','1,2,3','-1']</code> but it will never have an empty string.
So I want that the answer should be <code>[2,3,4,1,2,3,-1]</code></p>

<p>What is the best way to do so in terms of complexity as well as less code.</p>

<p>Thanks...</p>
