Aggregate items in dict
<p>I have a list like this:</p>

<pre><code>A = [{u'CI': {u'RP': 1}}, {u'CI': {u'RP': 1}},  {u'JI': {u'RP': 1}}]
</code></pre>

<p>and I want merge same keys and increment value in dict.</p>

<p>Example: </p>

<p>From these values : </p>

<pre><code>{u'CI': {u'RP': 1}}, {u'CI': {u'RP': 1}}
</code></pre>

<p>I will have: </p>

<pre><code>{u'CI': {u'RP': 2}}
</code></pre>

<p>final list result is:</p>

<pre><code>A = [{u'CI': {u'RP': 2}}, {u'JI': {u'RP': 1}]
</code></pre>
