def merge_label_equivalent(input_dict):
    """
    A function return output dict after merge all label equivalent

    @param:
        - input_dict (a collection label key with
                    another key set value before merge)
    @return:
        - output dict after merge all label equivalent
    """
    output_dict = {}
    i = 0
    list_key = list(input_dict.keys())
    while i < len(list_key):
        value = list(input_dict[list_key[i]])
        first_len = -2
        second_len = -1
        while first_len != second_len:
            first_len = len(value)
            for elm in value:
                value = list(set(value + list(input_dict[elm])))
            second_len = len(value)
            output_dict.update({list_key[i]: set(value)})
        i += 1
    return output_dict
