code: def _get_db():
      
      from .settings import settings
      mongo = settings.MONGODB
  
      if 'URI' in mongo and mongo['URI']:
          uri = mongo['URI']
      else:
          uri = 'mongodb://'
  
          if all(mongo.get(key) for key in ('USERNAME', 'PASSWORD')):
              uri += '{0}:{1}@'.format(mongo['USERNAME'], mongo['PASSWORD'])
  
          if 'HOSTS' in mongo and mongo['HOSTS']:
              uri += ','.join(
                  '{0}:{1}'.format(host, port)
                  for (host, port) in zip(mongo['HOSTS'], mongo['PORTS']),
              )
          else:
              uri += '{0}:{1}'.format(mongo['HOST'], mongo.get('PORT', 27017))
  
          uri += '/' + mongo['DATABASE']
  
          if 'OPTIONS' in mongo and mongo['OPTIONS']:
              uri += '?{0}'.format('&'.join(mongo['OPTIONS']))
  
      client = ConnectionFailureProxy(MongoClient(uri, connect=False))
      database = client[parse_uri(uri)['database']]
  
      return database
docs: Returns the connection to the database using the settings.
      This function should not be called outside of this file.
      Use db instead.