code: def percent_records_missing_location(user, method=None):
      
  
      if len(user.records) == 0:
          return 0.
  
      missing_locations = sum([1 for record in user.records if record.position._get_location(user) is None])
      return float(missing_locations) / len(user.records)
docs: Return the percentage of records missing a location parameter.