In this task, you are given a string of characters. You need to remove duplicate characters from the string if any, and return the resulting string.

[EX Q]: NppGiDtphEonPjnwXqBwfB
[EX A]: NpGiDthEonPjwXqBf

[EX Q]: ddoeHjaUVbJxtOpJywIOgn
[EX A]: doeHjaUVbJxtOpywIgn

[EX Q]: MVSgVVGyEUoNRFFkrTkrgLcYYSPPAX
[EX A]:
MVSgGyEUoNRFkrTLcYPAX