code: def test_predictor_holdout_iris():
      G.priority_callbacks = (DummyExperimentPredictorHoldout,)
  
      #################### Set Up Environment ####################
      env = Environment(
          train_dataset=get_iris_data(),
          results_path=assets_dir,
          holdout_dataset=get_holdout,
          target_column="species",
          metrics=dict(
              f1=lambda t, p: f1_score(t, p, average="micro"),
              hamming_loss="hamming_loss",
          ),
          cv_type="StratifiedKFold",
          cv_params=dict(n_splits=5, shuffle=True, random_state=32),
      )
  
      #################### Perform Experiment ####################
      experiment = CVExperiment(
          model_initializer=XGBClassifier,
          model_init_params=dict(
              objective="multi:softprob",
              max_depth=1,
              n_estimators=300,
              learning_rate=0.02,
              min_child_weight=6,
              gamma=0.07,
              colsample_bytree=0.31,
          ),
          model_extra_params=dict(
              fit=dict(
                  eval_set=[
                      (env.train_input, env.train_target),
                      (env.validation_input, env.validation_target),
                  ],
                  early_stopping_rounds=20,
                  eval_metric="merror",
              )
          ),
      )
  
      G.priority_callbacks = tuple()
  
imports: from hyperparameter_hunter import Environment, CVExperiment
  from hyperparameter_hunter.callbacks.bases import BaseCallback
  from hyperparameter_hunter.settings import G
  from hyperparameter_hunter.utils.learning_utils import get_breast_cancer_data
  from copy import deepcopy
  import pandas
  import pytest
  from sklearn.datasets import load_iris
  from sklearn.metrics import f1_score
  from sklearn.model_selection import train_test_split
  from sklearn.preprocessing import LabelEncoder
  from xgboost import XGBClassifier
label_desc: Use image node_id 3 for calling a global function with example usage: test_predictor_holdout_iris() without return types