#! /usr/bin/env python
input = open('in.txt', 'r')
output = open('out.txt', 'w')
linesarray = input.readlines()
input.close()
seen = []
for i in range(len(linesarray)):
    if seen.count(linesarray[i]) == 0:
        seen.append(linesarray[i])
        output.write(linesarray[i])
 output.close()

  if seen.count(linesarray[i]) == 0:

  if seen.count(linesarray[i]) == 0: # в списке seen нет строки linesarray[i]

#! /usr/bin/env python
input = open('in.txt', 'r')
output = open('out.txt', 'w')
linesarray = input.readlines()
input.close()
seen = []
for line in linesarray:
    if line not in seen:
        seen.append(line)    
 output.writelines(seen)