Python: list comparison
<p>please help me. If element in <code>b</code> is in <code>a</code>, then I want to put <code>a</code> (paired) in a new list (<code>C</code>).</p>

<pre><code>a=['SMAD3', 'CYP11A1']
['SMAD3', 'ZNF83']
['SMAD3', 'PSMD11']
['SMAD3', 'MTF2']
['SMAD3', 'CFDP1']
['SMAD3', 'ST6GALNAC2']...

b=['NPR2']
['COL2A1']
['GNPTAG']
['ENPP1']
['COL6A1']
['WISP3']...
</code></pre>

<p>I coded like this:</p>

<pre><code>C=[ ]
for data in a:
   for line in b:
  if ...
  C.append(a)
</code></pre>

<p>How can I fill the <code>if</code>?</p>
