lanx@nc10-ubuntu:~$ python
Python 2.5.2 (r252:60911, Jan 20 2010, 23:16:55) 
...
>>> str="123"
>>> str+="4"
>>> str
'1234'

##</code><code>##

  DB<1> $str="";$t=time;for (1..100000) {$str=$str."a"."b"};print time-$t
13
  DB<2> $str="";$t=time;for (1..1000000) {$str.="a";$str.="b"};print time-$t
1

##</code><code>##

>>> for i in range(1, 1000000):
...   str+="a"+"b"
... 
>>> str=""
>>> for i in range(1, 100000):
...   str=str+"a"+"b"
... 

##</code><code>##

  DB<1> $t=time;for (1..10000000) {$str="";$str.="a"."b";};print time-$t
10
  DB<2> $t=time;for (1..10000000) {$str="";$str=$str."a";$str.="b";};print time-$t
17
  DB<3> $t=time;for (1..10000000) {$str="";$str=$str."a"."b";};print time-$t
15