def split_data(df: pd.DataFrame, test_size=0.15, val_size=0.15):
X = df.loc[:, df.columns != 'Vote']
y = df['Vote']
sss = StratifiedShuffleSplit(n_splits=1, test_size=test_size, random_state=101)
train_val_indices, test_indices = next(sss.split(X, y))
sss.test_size = val_size / (1 - test_size)
train_indices, val_indices = next(sss.split(X.iloc[train_val_indices, :], y[train_val_indices]))
test_indices = df.iloc[sorted(test_indices), :].index
train_indices = df.iloc[train_val_indices, :].iloc[sorted(train_indices), :].index
val_indices = df.iloc[train_val_indices, :].iloc[sorted(val_indices), :].index
return sorted(train_indices), sorted(val_indices), sorted(test_indices)
