how to write a function to add the integer of corresponding letter in python?
<p>how to write a function to add the integer of corresponding letter in python?</p>

<p>for example:</p>

<pre><code>   L=[('a',3),('b',4),('c',5),('a',2),('c',2),('b',1)]
</code></pre>

<p>How to solve it by just loop over the item in L?</p>
