code: def getXRDExpiration(xrd_element, default=None):
      
      expires_element = xrd_element.find(expires_tag)
      if expires_element is None:
          return default
      else:
          expires_string = expires_element.text
  
          # Will raise ValueError if the string is not the expected format
          expires_time = strptime(expires_string, "%Y-%m-%dT%H:%M:%SZ")
          return datetime(*expires_time[0:6])
docs: Return the expiration date of this XRD element, or None if no
      expiration was specified.
  
      @type xrd_element: ElementTree node
  
      @param default: The value to use as the expiration if no
          expiration was specified in the XRD.
  
      @rtype: datetime.datetime
  
      @raises ValueError: If the xrd:Expires element is present, but its
          contents are not formatted according to the specification.