old_contents: 
  def filterTags(attrs):
      res = {}
  
      if 'NAMN' in attrs:
          res['name'] = attrs['NAMN']
  
      if 'TATNR' in attrs:
          res['ref:se:scb'] = attrs['TATNR']
  
      if attrs.get('BEF') is not None:
          bef = int(attrs.get('BEF'))
  
          # This is an approximation based on http://wiki.openstreetmap.org/wiki/Key:place
          # and the observed values of nodes in OpenStreetMap itself for cities and towns
          # around Sweden.
  
          # This seems to be around where OSM sets city status for Sweden
          if bef >= 30000:
              res['place'] = 'city'
          elif bef >= 6000:
              res['place'] = 'town'
          elif bef >= 200:
              res['place'] = 'village'
  
      return res
  
new_contents: 
  def filterTags(attrs):
      res = {}
  
      if 'NAMN' in attrs:
          res['name'] = attrs['NAMN']
  
      if 'TATNR' in attrs:
          res['ref:se:scb'] = attrs['TATNR']
  
      if attrs.get('BEF') is not None:
          bef = int(attrs.get('BEF'))
  
          # This is an approximation based on http://wiki.openstreetmap.org/wiki/Key:place
          # and the observed values of nodes in OpenStreetMap itself for cities and towns
          # around Sweden.
  
          # This seems to be around where OSM sets city status for Sweden
          if bef >= 30000:
              res['place'] = 'city'
          elif bef >= 6000:
              res['place'] = 'town'
          elif bef >= 200:
              res['place'] = 'village'
  
          res['population'] = str(bef)
  
      return res
  
subject: Add population to the tags