def accuracy(actual_y: list, predicted_y: list) -> float:
    """
    Calculate the value of accuracy based-on predictions
    :param actual_y:a list containing initial Y values generated by 'y_generator'
        function
    :param predicted_y: a list containing predicted Y values generated by
        'predict_y_values' function
    :return: percentage of accuracy
    """
    # iterate over one element of each list at a time (zip mode)
    # prediction is correct if actual Y value equals to predicted Y value
    correct = sum(1 for i, j in zip(actual_y, predicted_y) if i == j)
    # percentage of accuracy equals to number of correct predictions divided by number
    # of all data and multiplied by 100
    return (correct / len(actual_y)) * 100