How can I write a list without duplicate with only for, if and boolean

Question

My professor gave me an exercise where I write a function that returns a list without the duplicate to the old list. This is the code but I don\'t know how to write the meth

Answer 1

Is this considered cheating?

>>> distinct = lambda lst: list(set(lst))
>>> distinct([1,3,1,2,6])
[1, 2, 3, 6]
>>> distinct(['a','ab','a','ab'])
['a', 'ab']