'import module' vs. 'from module import function'
<p>I have always been using this method:</p>

<pre><code>from sys import argv
</code></pre>

<p>and use <code>argv</code> with just <strong>argv</strong>. But there is a convention of using this:</p>

<pre><code>import sys
</code></pre>

<p>and using the argv by <code>sys.argv</code></p>

<p>The second method makes the code self documented and I <em>(really)</em> adhere to it. But the reason I prefer first method is it is fast because we are importing only the function that is needed rather than import the whole module (which contains more useless functions which python will waste time importing them). Note that I need just argv and all other functions from sys are useless to me.</p>

<p>So my questions are. Does the first method really makes the script fast? Which method is preferred most? Why?</p>
