In this task, you will be given a sentence, and you need to identify the set of coreference words. Coreferences are generally a set of words in the text that refer to the same person or thing. Your output set of coreference words must be strictly present in the given input sentence. Do not use any outside knowledge to create the set of coreference words. If there is a 'the' article before the person or thing you should include 'the' as well. Please separate the coreference words by commas in the output.
One example: The developer argued with the designer because he did not like the design.
Solution is here: The, developer, he
Explanation: Here the output set of coreference words 'The', 'developer, and 'he' refer to the same person, and these are coreferences. So, the output is correct.

Now, solve this: The chief gave the housekeeper a tip because she was helpful .
Solution:
the, housekeeper, she