def select_option(prompt, valid_response_set):
    """Select an option from a set of options.

    :param prompt: Message to display before displaying option.
    :type prompt: str
    :param valid_response_set: Set of valid options to choose.
    :type valid_response_set: set
    :returns: option
    :rtype: str, int
    """
    response_valid = False
    while response_valid == False:
        response = input(prompt)
        if response.isdigit():
            response = int(response)
        else:
            response = response.lower()
        if response in valid_response_set:
            response_valid = True
            if response == 'y':
                response = 'yes'
            elif response == 'n':
                response = 'no'
        else:
            print('Invalid response.')
    return response
