def unique(input_list):
    """
    Return a list of unique items (similar to set functionality).

    Parameters
    ----------
    input_list : list
        A list containg some items that can occur more than once.

    Returns
    -------
    list
        A list with only unique occurances of an item.

    """
    output = []
    for item in input_list:
        if item not in output:
            output.append(item)
    return output