title: Parsing multiple root XML file in Python
body: <p>I am a beginner in Python.
  I use Python 2.7 with ElementTree to parse XML files.
  I have a big XML file (~700 MB), which contains multiple root instances, for example:</p>
  
  <pre><code> &lt;?xml version="1.0" ?&gt; &lt;foo&gt; &lt;bar&gt; &lt;sometag&gt; Mehdi  &lt;/sometag&gt; &lt;someothertag&gt; blahblahblah &lt;/someothertag&gt; . . . &lt;/bar&gt; &lt;/foo&gt;
   &lt;?xml version="1.0" ?&gt; &lt;foo&gt; &lt;bar&gt; &lt;sometag&gt; Hamidi &lt;/sometag&gt; &lt;someothertag&gt; blahblahblah &lt;/someothertag&gt; . . . &lt;/bar&gt; &lt;/foo&gt;
  ...
  ...
  </code></pre>
  
  <p>each xml instance is placed in one line.
  I need to parse such file in python. I used ElementTree this way:</p>
  
  <pre><code>import xml.etree.ElementTree as ET
  tree = ET.parse('filename.xml')
  root = tree.getroot()
  </code></pre>
  
  <p>but it seems it just can access to the first root XML instance line.
  What is the proper way to parse all XML instances in this type of file?</p>