def train_test_split(df, **options):
    """
    Split input data to train and test data.

    Parameters
    ----------
    df : modin.pandas.DataFrame / modin.pandas.Series
        Data to split.
    **options : dict
        Keyword arguments. If `train_size` key isn't provided
        `train_size` will be 0.75.

    Returns
    -------
    tuple
        A pair of modin.pandas.DataFrame / modin.pandas.Series.
    """
    train_size = options.get("train_size", 0.75)
    train = df.iloc[: int(len(df) * train_size)]
    test = df.iloc[len(train) :]
    return train, test