Cycle through the following operations one at a time until no further operations can be performed:

1. If the string contains 'abc', replace the first occurrence with 'cab'.
2. If the string contains 'ca' (not at the start), remove the first occurrence found after the first character.
3. If the string ends with 'ba', replace it with 'ab'.
4. If the string ends with 'ca', remove the last character.
5. If the string contains an even number of 'b's (and at least one 'b'), append 'ab' at the end.
6. If the string prefix is 'aa', remove the first character.

For the string "abcbabaccacaba", what is the final string after performing all operations?

Provide your answer as a string in the following format:

<<< "some_final_string" >>>
