code: def split_data(X, y, ratio=(0.8, 0.1, 0.1)):
      
      assert(sum(ratio) == 1 and len(ratio) == 3)
      X_train, X_rest, y_train, y_rest = train_test_split(
          X, y, train_size=ratio[0])
      X_val, X_test, y_val, y_test = train_test_split(
          X_rest, y_rest, train_size=ratio[1])
      return X_train, X_val, X_test, y_train, y_val, y_test
docs: Splits data into a training, validation, and test set.
  
          Args:
              X: text data
              y: data labels
              ratio: the ratio for splitting. Default: (0.8, 0.1, 0.1)
  
          Returns:
              split data: X_train, X_val, X_test, y_train, y_val, y_test