duplicate_list = [56, 4, 81, 56, 9, 4]
print(duplicate_list)

cleaned_list = list(set(duplicate_list))
print(cleaned_list)
# [56, 81, 4, 9]

cleaned_list = list(dict.fromkeys(duplicate_list))
print(cleaned_list)
# [56, 4, 81, 9]

# dict.fromkeys() creates this:
cleaned_list = dict.fromkeys(duplicate_list)
print(cleaned_list)
# {56: None, 4: None, 81: None, 9: None}