def attending_info_detect(in_data):
    """Detect if the email address is validate or not

    See if the email address include the @ sign to determine if it is a valid
    email address

    Args:
        in_data (dict): The dictionary that includes the attending's email
        address

    Returns:
        str or True: Indicate if it is a valid email address

    """
    good_email = "@" in in_data["attending_email"]
    if good_email is not True:
        return "You entered a invalid email address, "
    return True