A list and it's positions : I'm creating a code where you enter a sentence, it splits each word in the sentence to become a separate member. When I enter a word, and I enter it again, those two words will have the same position below. For instance,

This is a This is a 
 1   2  3  1    2 3

The problem is, that my code does this differently, for example, 

This This Is Is 
 1     1   2  3

If it's done it twice, it will just continue to count forever.

Here is my code:

sent = input("Enter your sentence:").lower()
sentlist = sent.split()
print (sent)


if len(sent) < 1:

    print ("No value entered. ")
    exit()

for i in sentlist:
    if sentlist.index(i) in newlist:
        newlist.append(sentlist.index(i))
    else:
        newlist.append(int(count))
        count = count + 1

Hopefully someone can help me..
Thanks stack gods.