Find an element in a list of tuples
<p>I have a list 'a'</p>

<pre><code>a= [(1,2),(1,4),(3,5),(5,7)]
</code></pre>

<p>I need to find all the tuples for a particular number. say for 1 it will be</p>

<pre><code>result = [(1,2),(1,4)]
</code></pre>

<p>How do I do that. </p>

<p>PS - This is not homework</p>
