Suppose you have a text file and you need to remove all of its duplicate lines.
TL;DR
To remove the duplicate lines while preserving their order in the file, use:
Standing just over 2 meters and hailing from о́стров Ратма́нова, Dasuberworm is a professional cryptologist, entrepreneur and cage fighter. When he's not breaking cyphers and punching people in the face, Das enjoys receiving ominous DHL packages at one of his many drop sites in SE Asia.
