code: def empty(self):
      return len(self) == 0
  
imports: import warnings
  from bayes_opt.constraint import ConstraintModel
  from .target_space import TargetSpace
  from .event import Events, DEFAULT_EVENTS
  from .logger import _get_default_logger
  from .util import UtilityFunction, acq_max, ensure_rng
  from sklearn.gaussian_process.kernels import Matern
  from sklearn.gaussian_process import GaussianProcessRegressor
label_desc: Use image node_id 2 for calling the Queue obj's underlying member method code with example usage: obj.empty() and returns: unknown