Create list from txt file, sort, and append.

Question

I know I know I can do this with a for loop but I want to do it this way first.
I need to create a list from a text file, sort it, then remove any repeated words.
I have created a list and sorted it.
need to append the list and remove any repeated words and can't figure out how.
this is what I have.. ( again yes I know a for loop would likely be cleaner but I want to do it this way first)
fname = input("Enter file name: ")
fh = open(fname)
words = fh.read()
words2 = words.rstrip()
words3 = words2.split()
words3.sort()
print(words3)
works fine up to this point.. but I know I will need a loop after this point to remove and repeated words.
['Arise', 'But', 'It', 'Juliet', 'Who', 'already', 'and', 'and', 'and', 'breaks', 'east', 'envious', 'fair', 'grief', 'is', 'is', 'is', 'kill', 'light', 'moon', 'pale', 'sick', 'soft', 'sun', 'sun', 'the', 'the', 'the', 'through', 'what', 'window', 'with', 'yonder']

Answer 1

You can convert it to set() before sort()
Sets can only contain unique elements so you'll have your job done this way :)

Answer 2

Oh, it's really simple. You should read it almost like in English: "if i (is) not in words4, append (it)."
Another words: if it is already in words4, do not append it again.
But I prefer a non-loop solution with set ;)
words3 = sort(set(words2.split()))
print(words3)

Answer 3

Well I just randomly too a stab it with this..
fname = input("Enter file name: ")
fh = open(fname)
words = fh.read()
words2 = words.rstrip()
words3 = words2.split()
words3.sort()
words4 = []
for i in words3:
if i not in words4:
words4.append(i)
print(words4)
and it worked fine.. however I do not understand the for loop very well. especially the "not in" .. it does not make much logical sense to me.