def describe_list_indices(full_list):
    """
    Describe the indices of the given list.

    Parameters
    ----------
    full_list : list
        The list of items to order.

    Returns
    -------
    unique_elements : list
        A list of the unique elements of the list, in the order in which
        they first appear.
    element_indices : dict
        A dictionary of lists for each unique element, giving all the
        indices in which they appear in the original list.

    """
    unique_elements = []
    element_indices = {}

    for i in range(len(full_list)):
        item = full_list[i]
        # new item
        if item not in unique_elements:
            unique_elements.append(item)
            element_indices[item] = [i]
        # previously seen item
        else:
            element_indices[item].append(i)
    return unique_elements, element_indices