def unique(lst):
    """
    Identify the unique elements of a list (the elements that do not appear 
    anywhere else in the list)
    """
    un_lst = []
    for i,v in enumerate(lst):
        if i == len(lst) - 1:
            continue
        if v != lst[i-1] and v != lst[i+1]:
            un_lst.append(i)
          
    return un_lst