def make_columns(repetitions, n_splits):
    """Provides column names for the tables of all predictions (from each
    split of each rep).

    Parameters
    ----------
    repetitions : int
        Repetitions of the n-fold validation
    n_splits : int
        number of splits in KFold

    Returns
    -------
    list
        List of the column names as strings
    """
    reps = range(repetitions)
    splits = range(n_splits)
    pre_cols = [[f'rep{i}_split{j}' for j in splits] for i in reps]
    cols = [item for sublist in pre_cols for item in sublist]
    return cols