def exp_transformation(data, orig_col, new_col, power):
    """
    Performs feature transformation by raising the indicated feature column to
    the given power.

    Parameters:
    _________________
    data:     dataframe containing training data
    orig_col: (str) column in data to be transformed
    new_col:  (str) header for new transformed column
    power:    (int) number to raise the original column by

    Returns:
    _________________
    transformed_df: new dataframe with transformed column added as the last col
    """
    transformed_df = data.withColumn(new_col, pow(data[orig_col], power))
    print('The transformed DataFrame is:')
    transformed_df.show()
    return transformed_df