Remove duplicate items from list

Question

how to Remove duplicate items from list and leave only one items from every duplicated:
ex : a = [1,1,1,2,2,2,3,3,3]
result = [1,2,3]

Answer 1

#You can also do like this
a = [1,6,1,4,6,9,1,6,9,1]
uniq = []
for i in a:
if i not in uniq:
uniq.append(i)
print(uniq)

Answer 2

set sorts the list and can only hold a value once so duplicates are removed. If you wish to maintain the original order, this can be used.

https://code.sololearn.com/cdXh680icSEt

Answer 3

# Convert to a set and back into a list.

num= set(a)
result = list(num)
print(result)

Answer 4

sets have only unique elements

Answer 5

why when convert to set duplicated remove ?