How to convert Pair RDD Tuple key to String key in Pyspark? : <p>I have created rdd like below </p>

<pre><code>rdd=sc.parallelize([('AA', 44),('BB', 53),(('AA', 'Bb'), 23), (('AD', 'AC'), 23),(('AA', 'BB', 'CC'), 2)])
</code></pre>

<p>I want convert tuple key to string.</p>

<p>My expected output is like below <code>new_rdd.collect()</code> should give:</p>

<pre><code>[('AA', 44),('BB', 53),('AA,Bb', 23),('AD,AC', 23),('AA,BB,CC',2)]
</code></pre>
