docs: def backup(app):
      """Dump the database."""
      dump_path = dump_database(app)
  
      config = PsiturkConfig()
      config.load_config()
  
      conn = boto.connect_s3(
          config.get('AWS Access', 'aws_access_key_id'),
          config.get('AWS Access', 'aws_secret_access_key'),
      )
  
      bucket = conn.create_bucket(
          app,
          location=boto.s3.connection.Location.DEFAULT
      )
  
      k = boto.s3.key.Key(bucket)
      k.key = 'database.dump'
      k.set_contents_from_filename(dump_path)
      url = k.generate_url(expires_in=0, query_auth=False)
  
      log("The database backup URL is...")
      print(url)