def get_var_type_size(ref, alt):
    """
    Calculate the variant type SNV, INS or DEL and length
    :param ref: String
    :param alt: String
    :return: var_type and var_size
    """
    var_size = len(alt) - len(ref)
    if var_size == 0:
        var_type = 'SNV'
    elif var_size > 0:
        var_type = 'INS'
    else:
        var_type = 'DEL'
    return var_type, var_size