Finding repetition in string

[student8]

I am a python newbie and I am trying to make a function that returns True if a given str is nonrepetitive and False otherwise.

For example,
>>> nonrepetitive("abcab")
True
>>> nonrepetitive("12341341")
False

Hints I was given was that I could ask if two strings are equal to each other and to use slicing

The following is what I have so far:

def repetitive(s):
     for i in s:
          if i == [i]+1:
               return True
          else:
               false

Please if anyone can help me out that would be appreciated

[Larz60+]

There appears to be repetition in both strings.
1st has ab repeated,
2nd has 34 and 41 repeated.
What are the complete rules on what constitutes repetitiveness?

[student8]

There appears to be repetition in both strings.
1st has ab repeated,
2nd has 34 and 41 repeated.
What are the complete rules on what constitutes repetitiveness?

A nonrepetitive word is a word that does not contain any subword twice in a row. Examples:
ana is nonrepetitive.
borborygmus is not nonrepetitive, since it has subword, bor twice in a row.
abracadabra is nonrepetitive.
repetitive is not nonrepetitive since subword ti is repeated twice in a row.
grammar is not nonrepetitive since subword m is repeated twice in a row.
gaga is not s nonrepetitive since subword ga is repeated twice in a row.
rambunctious is nonrepetitive.
abcab is nonrepetitive.
abacaba is nonrepetitive.
zrtzghtghtghtq is not nonrepetitive since subword ght is repeated twice (in fact three times, but it is enough to find two
repetitions to conclude that the word is not nonrepetitive).
aa is not nonrepetitive since subword a is repeated twice.
zatabracabrac is not nonrepetitive since subword abrac is repeated twice in a row.

[ichabod801]

This is going to take a couple loops: you will need to loop through indexes and lengths. For each index (starting character) you need to check each length to see if a subword of the string is repeated twice.

[student8]

This is going to take a couple loops: you will need to loop through indexes and lengths. For each index (starting character) you need to check each length to see if a subword of the string is repeated twice.

How do you check each length of a string?