code: def train_data(breast_cancer_split):
      X_train, _, y_train, _ = breast_cancer_split
      return lgb.Dataset(X_train, y_train)
  
imports: import numpy
  import pandas
  import pytest
  from sklearn.model_selection import train_test_split
  import lightgbm
  from lightgbm.compat import GRAPHVIZ_INSTALLED, MATPLOTLIB_INSTALLED, PANDAS_INSTALLED, pd_DataFrame
  from .utils import load_breast_cancer, make_synthetic_regression
label_desc: Use image node_id 3 for calling a global function with example usage: train_data(breast_cancer_split) and returns: lgb