// for stuff like #1000349

static class LFixedPositions extends LearnerImpl {
  static boolean debug;
  Map<Integer, String> map = new TreeMap<Integer, String>();

  public void processInOut(Object _in, Object _out) {
    // Only looks at out... funny, eh?
    
    String out = cast _out;
    for (int i = 0; i < out.length(); i++) {
      String s = map.get(i);
      String c = out.substring(i, i+1);
      if (s == null)
        map.put(i, c);
      else if (s.equals("")) {
      } else if (!s.equals(c))
        map.put(i, ""); // TILT
    }
    
    for (int i : map.keySet())
      if (i >= out.length())
        map.put(i, "");
  }
  
  public Object processIn(Object _in) {
    String in = cast _in;
    new List<String> l;
    for (int i = 0; i < in.length(); i++)
      l.add(in.substring(i, i+1));
    for (int i : map.keySet()) {
      String s = map.get(i);
      if (!s.equals("")) {
        while (i >= l.size())
          l.add(" ");
        l.set(i, s);
      }
    }
    return join("", l);
  }
}

Began life as a copy of #1000481