TASK DEFINITION: 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.
PROBLEM: XttLMRTVbiQDKPMEXyeXPSoDGCehY

SOLUTION: XtLMRTVbiQDKPEyeSoGChY

PROBLEM: pfnVbGKENymodcvWtfDkdCzPhO

SOLUTION: pfnVbGKENymodcvWtDkCzPhO

PROBLEM: tHKixfuMiKESMqerSljlnIarbDl

SOLUTION:
tHKixfuMESqerljnIabD