import itertools


def remove_duplicates(in_list):
    """
        This function removes duplicates in the input list, where
        input list is composed of unhashable elements
        Example:
            in_list = [[1,2],[1,2],[2,3]]
            output = remove_duplicates(in_list)
            output --> [[1,2].[2,3]]
    """
    out_list = []
    in_list.sort()
    out_list = list(in_list for in_list, _ in itertools.groupby(in_list))
    # print("input_list: ", in_list)
    # print("output list: ",out_list)
    return out_list