def pick_char(array0):
 unique = []
 duplicate = []
 for i in array0:
  if (i in duplicate):
   pass
  elif (i in unique):
   duplicate.append(i)
   unique.remove(i)
  else:
   unique.append(i)
 return unique[0]

def pick_char ( array0 ) : unique = [ ] duplicate = [ ] for i in array0 : if ( i in duplicate ) : pass elif ( i in unique ) : duplicate . append ( i ) unique . remove ( i ) else : unique . append ( i ) return unique [ 0 ]
array0: list .