Unique lists from a list
Question: Given a list I need to return a list of lists of unique items. I'm looking to
see if there is a more Pythonic way than what I came up with:

    
    
    def unique_lists(l):
        m = {}
        for x in l:
            m[x] = (m[x] if m.get(x) != None else []) + [x]
        return [x for x in m.values()]    
    
    print(unique_lists([1,2,2,3,4,5,5,5,6,7,8,8,9]))
    

Output:

    
    
    [[1], [2, 2], [3], [4], [5, 5, 5], [6], [7], [8, 8], [9]]
    


Answer: 
    >>> L=[1,2,2,3,4,5,5,5,6,7,8,8,9]
    >>> from collections import Counter
    >>> [[k]*v for k,v in Counter(L).items()]
    [[1], [2, 2], [3], [4], [5, 5, 5], [6], [7], [8, 8], [9]]
    

