Fonction Thue Morse

Function Thue_Morse (ch:String): String;
Var
  x: String;
  i: Integer;
Begin
  x := '';
  For i:=1 To Length (ch) Do
    Begin
      If ch[i]='0' Then
        x := x+'01';
      If ch[i]='1' Then
        x := x+'10';
    End;
  Thue_Morse := x;
End;