title: AttributeError: 'ElementTree' object has no attribute 'tag' in Python
body: <p>I want to parse an XML file and extract the nodes that I am interested in if the nodes contain a specific string (keyword). But to use find and finall functions, first I decided to lower case the list of the keywords that I have, as well as the XML file.
  Here is code.</p>
  
  <pre><code>import xml.etree.ElementTree as ET
  from xml.etree.ElementTree import tostring
  import csv
  tree=ET.parse('/Users/m/Documents/dr.xml')
  **t = tostring(tree)**
  t = t.lower()
  tree= ET.fromstring(t).......
  </code></pre>
  
  <p>I get error on this line:</p>
  
  <pre><code>t = tostring(tree)
  </code></pre>
  
  <p>Any idea how this can be fixed?
  Thx</p>