def data_exclude(conf):
    # type: (dict) -> str
    """Retrieve input data exclude filters
    :param dict conf: configuration object
    :rtype: str
    :return: exclude filters
    """
    try:
        exclude = conf['exclude']
        if exclude is not None and len(exclude) == 0:
            exclude = ''
        else:
            exclude = ';'.join(exclude)
    except KeyError:
        exclude = ''
    if exclude is None:
        exclude = ''
    return exclude