code: def _get_severity(c):
      
      severities = c.feu.xpath('event-indicators/event-indicator/event-severity/text()|event-indicators/event-indicator/severity/text()')
      impacts = c.feu.xpath('event-indicators/event-indicator/event-impact/text()|event-indicators/event-indicator/impact/text()')
  
      severities = [convert_severity[s] for s in severities]
      impacts = [convert_impact[i] for i in impacts]
  
      return ['UNKNOWN', 'MINOR', 'MODERATE', 'MAJOR'][max(itertools.chain(severities, impacts))]
docs: 1. Collect all <severity> and <impact-level> values.
      2. Convert impact-level of 1-3 to MINOR, 4-7 to MODERATE, 8-10 to MAJOR
      3. Map severity -> none to MINOR, natural-disaster to MAJOR, other to UNKNOWN
      4. Pick the highest severity.