What does the parameter "stratify" refer to in the "train_test_split" method of scikit learn?

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The parameter "stratify" in the "traintestsplit" method of scikit learn refers to the optional argument that is used to ensure that the split is representative of the data. When the "stratify" parameter is set to a categorical variable, the split is ensured to have the same ratio of the categorical variable in each subset as the original dataset. This is useful when the categorical variable is imbalanced, and we want to ensure that each subset has a representative sample of the different categories.