<oerjan> addquote <ais523> b_jonas: hmm, it\'s fairly surprising that you can make a coherent esolang whose primary feature is that it wasn\'t written by Donald Knuth

#!/usr/bin/python
s=set()
try:
 while True:
  l=raw_input()
  if l not in s:
   s.add(l)
   print(l)
except EOFError:
 pass