def get_duplicates(items):
    """
    gets a list of duplicate items in given list of items.

    :param list | tuple | set items: items to be checked for duplications.

    :rtype: list
    """

    unique_set = set(items)
    if len(unique_set) == len(items):
        return []

    duplicates = []
    for item in unique_set:
        if items.count(item) > 1:
            duplicates.append(item)

    return duplicates