add something to nametuple
<p>I build</p>

<pre><code>Corpus = collections.namedtuple('Corpus', 'a, b, c, d')
</code></pre>

<p>Read all the files in the corpus and save the data,</p>

<pre><code>def compute(counters, tokens, catergory)
    ...
    counters.stats[tokens][catergory] = Corpus(a, b, c, d)
</code></pre>

<p>Both tokens and catergory are collection.Counter(). After reading all the information in a, b, c, d in counters.stats, I do some calculation in another function and get 'e' for each token. How can I add e into counters.stats in this function?</p>
