def mutual_information_calc(response_entropy, conditional_entropy):
    """
    Calculate Mutual information.

    :param response_entropy: response entropy
    :type response_entropy: float
    :param conditional_entropy: conditional entropy
    :type conditional_entropy: float
    :return: mutual information as float
    """
    try:
        return response_entropy - conditional_entropy
    except Exception:
        return "None"