text: import xml.etree.ElementTree as ET
  
  
  def exercise(xml):
      """Iterate over all title elements, make their content uppercase, and return
      the modified XML string.
      """
      ns = {"t": "http://martin.hoppenheit.info/code/generic-tree-xml",
            "e": "http://purl.org/dc/elements/1.1/"}
      root = ET.fromstring(xml)
      for t in root.iter("{%s}title" % ns["e"]):
          t.text = t.text.upper()
      for prefix, uri in ns.items():
          ET.register_namespace(prefix, uri)
      return ET.tostring(root, encoding="unicode")
  
  
  if __name__ == "__main__":
      with open("../xml/example.xml") as f:
          xml = f.read()
          print(exercise(xml))
  