title: Python XML findall does not work
body: <p>I am trying to use findall to select on some xml elements, but i can't get any results.</p>
  
  <pre><code>import xml.etree.ElementTree as ET
  import sys
  
  storefront = sys.argv[1]
  
  xmlFileName = 'promotions{0}.xml'
  
  xmlFile = xmlFileName.format(storefront)
  
  csvFileName = 'hrz{0}.csv'
  csvFile = csvFileName.format(storefront)
  ET.register_namespace('', "http://www.demandware.com/xml/impex/promotion/2008-01-31")
  tree = ET.parse(xmlFile)
  
  root = tree.getroot()
  print('------------------Generate test-------------\n')
  
  
  
  csv = open(csvFile,'w')
  n = 0
  for child in root.findall('campaign'):
      print(child.attrib['campaign-id'])
      print(n)
      n+=1
  </code></pre>
  
  <p>The XML looks something like this:</p>
  
  <pre><code>  &lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;promotions xmlns="http://www.demandware.com/xml/impex/promotion/2008-01-31"&gt;
      &lt;campaign campaign-id="10off-310781"&gt;
          &lt;enabled-flag&gt;true&lt;/enabled-flag&gt;
          &lt;campaign-scope&gt;
              &lt;applicable-online/&gt;
          &lt;/campaign-scope&gt;
          &lt;customer-groups match-mode="any"&gt;
              &lt;customer-group group-id="Everyone"/&gt;
          &lt;/customer-groups&gt;
      &lt;/campaign&gt;
  
      &lt;campaign campaign-id="MNT-deals"&gt;
          &lt;enabled-flag&gt;true&lt;/enabled-flag&gt;
          &lt;campaign-scope&gt;
              &lt;applicable-online/&gt;
          &lt;/campaign-scope&gt;
          &lt;start-date&gt;2017-07-03T22:00:00.000Z&lt;/start-date&gt;
          &lt;end-date&gt;2017-07-31T22:00:00.000Z&lt;/end-date&gt;
          &lt;customer-groups match-mode="any"&gt;
              &lt;customer-group group-id="Everyone"/&gt;
          &lt;/customer-groups&gt;
      &lt;/campaign&gt;
  
      &lt;campaign campaign-id="black-friday"&gt;
          &lt;enabled-flag&gt;true&lt;/enabled-flag&gt;
          &lt;campaign-scope&gt;
              &lt;applicable-online/&gt;
          &lt;/campaign-scope&gt;
          &lt;start-date&gt;2017-11-23T23:00:00.000Z&lt;/start-date&gt;
          &lt;end-date&gt;2017-11-24T23:00:00.000Z&lt;/end-date&gt;
          &lt;customer-groups match-mode="any"&gt;
              &lt;customer-group group-id="Everyone"/&gt;
          &lt;/customer-groups&gt;
          &lt;custom-attributes&gt;
              &lt;custom-attribute attribute-id="expires_date"&gt;2017-11-29&lt;/custom-attribute&gt;
          &lt;/custom-attributes&gt;
      &lt;/campaign&gt;
  
      &lt;promotion-campaign-assignment promotion-id="winter17-new-bubble" campaign-id="winter17-new-bubble"&gt;
          &lt;qualifiers match-mode="any"&gt;
              &lt;customer-groups/&gt;
              &lt;source-codes/&gt;
              &lt;coupons/&gt;
          &lt;/qualifiers&gt;
          &lt;rank&gt;100&lt;/rank&gt;
      &lt;/promotion-campaign-assignment&gt;
  
      &lt;promotion-campaign-assignment promotion-id="xmas" campaign-id="xmas"&gt;
          &lt;qualifiers match-mode="any"&gt;
              &lt;customer-groups/&gt;
              &lt;source-codes/&gt;
              &lt;coupons/&gt;
          &lt;/qualifiers&gt;
      &lt;/promotion-campaign-assignment&gt;
  
  &lt;/promotions&gt;
  </code></pre>
  
  <p>Any ideas what i am doing wrong?
   I have tried different solutions that i found on stackoverflow but nothing seems to work for me(from the things i have tried).
   The list is empty.
   Sorry if it is something very obvious i am new to python.</p>