How to know the filetype through python
<p>In the very beginning,I tried to do like this(hoped to get some useful information in the head):<br/></p>

<pre>
>>content=open("fileurl","rb").read()
</pre>

<p>I found that PNG (png)'s Header  is lik this: 89504E47 (I don't know wheather it's true or not)<br/>
But when I did in this way,the result is:<br/></p>

<pre>
>>> content[:20]
'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x01\x90'

</pre>

<p>the <code>\x</code>is what?<br/>
Hope someone can help!Thanks very much!</p>
