.py

#  test cases;
 # extract_unique_elements([2])
 # extract_unique_elements([[[[5, 5]]]])
 # extract_unique_elements([2, 2, 3, [[[3]]]])    FAILED
 # extract_unique_elements([[3, [3, [[3]]]]])
 # extract_unique_elements([2, [[2, 4, 5]], 'c', [[['c', 'd']]]])   FAILED
 
def extract_unique_elements(a_list):
    if isinstance(a_list, list) == False:
        return {a_list}
    uniq = {}
    for element in a_list:
        if isinstance(a_list,list):
            return extract_unique_elements(element)
        else:
            uniq.add(element)